All non-virtual geocaches must contain a logbook. If it must contain a logbook for you to sign, then you must sign said logbook. If your name is not in the logbook then you have not truly found the geocache. Bring something to mark in the logbook if you you would like to count the find.
In your log I would love to have you finish this sentence, not required, but totally worth it! I will try to update this list with what you guys add! 
You might be a geocacher if...
...you have a set of clothes in your car for every caching expedition... and likely a spare for that too...
...you have a shovel and many garbage bags in there as well...
...you are covered in scrapes, bruises and scars... and each one tells a different awesome, sometimes unbelievable tale...
...you spend your weekends doing crazy things...
...you look like you have a drug problem because of the amount of empty pill bottles you carry around with you...
..TOTTS occupy your thoughts...
...you often step out at lunch time and climb snowbanks in your dress shoes to make the find.
... you can MacGyver a TOTT from what is at hand.
...You have spend thousands and thousands of dollars playing this FREE game and have even bought a camper trailer for more geocaching adventures!!!
...you get stopped by the police asking why you are parked illegally and you reply "That's OK, be done in two minutes--just waiting for my wife to bring me the cash!" Oops...
...you're used to trying to explain having twigs in your hair and pine needles stuck to you when you return from lunch break...
...any direction between where you are and where you need to be is "on the way"
...your dog has learned to excitedly react to the beeping sounds of coordinates being entered into a GPS at home.
...you faithfully download PQ's and maintain a GSAK database weekly on Thursdays, Fridays, and Saturdays to be ready for the next caching trip, even though you have no plans to go anywhere near a cache for the foreseeable future.
... you take a sudden right turn onto a gravel road because you remembered at the last second that a new cache was down here.
...you drive from the south side of city to the extreme north side to pick up a new geocache.
...search out caches that start with the letter Y for a challenge that you signed in on a few years ago.
...see that a cache is down a mud road and you figure your sub compact can make it there and back.
...You travel 22 hours to the Polar Bear Capital of the World and have an event on the shoreline where hundreds of the world's largest predators roam just so you can claim your Nunavut souvenir
...You look at geocaches as mini adventures to be enjoyed with friends and loved ones, and you are always looking forward to the next one
...your thought process is; Geocaching; Sleep, food, hygiene.....
...You take your caching vehicle down roads you really shouldn't, even when the CO tells you not to
...You think nothing of doing a 20km hike to find one or two geocaches
...For your birthday you receive your very own custom made stamp so you can sign into geocaches more easily, and you think it's the best present ever!!!
...You own a pair of scientifically engineered super sandals that are perfect for late winter/early spring caching!!!!
...Your idea of a perfect date with your girl friend is to walk along an abandoned rail line in the middle of no where and place plastic containers in trees
...You scheme and plot of ways to smuggle your significant other across international borders just so she can claim a couple new geocaching souvenirs and the hell with the consequences!
...You go out of your way to find and log a cache of someone you care about, just so you can write witty (?) and funny stories in your cache log, all in the hope that she will read it and it will brighten her day just a little bit
...you’ve conceited “Yeah, Kinda” when people ask you if caching is like Pokémon Go
...you might be a geocacher if you work on puzzles way past midnight.
...it takes you six hours to drive 200 km, thanks to all of the stops along the way.
...peanut butter sandwiches are a process towards the goal of getting more cache containers.
....you are the one netleyhunter told not to drive there!!
....planning vacations around old caches and new souvenirs.
....the police like to talk to you while you are half way up a tree.
....enjoying geography and geology now comes with a smiley.
....the trunk of the car is a caching supply storage locker.
....cold winter days are less cold when other cachers bring you big smileys.
... you keep a pair of snowshoes in your trunk at all times!
... you MUST go outside, regardless of the weather, and continue the pursuit of the smiley even after getting a booter filled with ice.
... you carry extra bags to cover the floor mats when you have to run through the mud, then gravel to get a smiley
... you don't always read the whole description before logging the find
... you're ready to tackle anything at a moment's notice (bing!)
...you pack a lunch, rubbers, baby & puppies in your vehicle to grab a few caches because you just aren't sure how many caches you will grab or how long it will take you!!
... you check out the height of every ladder you see and give directions by cache location!
...while on your exercise and geocaching mission you need your bike for a lift to get at that cache that is out of reach.
...you know the significance of TFTC. And of course the importance of it to me.
... you clean your car in the spring and find a couple missing trackables.
... you reject idea of a 20 mins. fitness walk, but would gladly walk all day collecting caches
... you get friendly with ticks and call them travel bugs.
... a new notification comes in and you don't have a pen so you go to coop and ask for a pen and still get the ftf! (We didn't even have to buy it!)
...you are making random puzzles for caches you haven't even hid yet...
...you sneak out of bed at night to quietly race for a ftf
...you are doing power trails and one wife is hanging out the hatchback grabbing the caches!
... you reject idea of a 20 mins. fitness walk, but would gladly walk all day collecting caches...
... you get friendly with ticks and call them travel bugs...
... you ignore windchill values ...
...you are covered in scrapes, bruises and scars... and each one tells a different awesome, sometimes unbelievable tale...
.... you smack your head more than once for the under the bridge hide that’s on the same road as this cache!
....When you are board You think nothing of doing a 20km hike to find one or two geocaches.
...you come home from caching with 50 ticks on your pants.
... you ignore all the DANGER signs and keep looking for the cache anyway.
... those warning signs that read "Not an all weather road" are taken as a personal challenge to see just how far you can push your brand new geomobile.
...your family asks "why, is there a cache nearby?" when you suggest going anywhere or doing anything!
... you drive clear to the opposite end of town with no productive goal in mind. Except finding a cache like this of course.
...you go out on a miserably cold, windy day and get caches on a wide open, bald Prairie, When you could be at home in your toasty recliner doing your other favourite hobby, Cross stitching.
... you plan all your travelling around how many souvenirs and countries you can add to your statistics!
...you secretly have an inner hatred for evergreen pine trees!
... you are told to practice "social distancing" and you hear "go Geocaching."
..., every where you go that's remotely interesting you say, I bet there's a geocache somewhere around here 
... you treat every other person in the area with suspicion and immediately think muggler
...you keep high rubber boots in your car at all times in case of wet ditches or poison ivy.
...you brought a certain TOTT to this cache based strictly on who the hider was.
...your hiking poles suddenly become very useful TOTT.
...you say just one more, three more times.
...you go looking for a cash on a cold, windy, wet day
...you plan your holidays around finding certain geocaches to fill the grids and requirements for challenge caches you have previously signed!!!!
...you look at everything as a potential hiding spot.
...you spend more time waiting for a guy walking his dog to be out of sight, then you actually spent looking for the cache and thought that was fun!!!
...you drive down a dirt road out of your way to get your birthday cache.
...you have to put your kid on your shoulders because they don’t like the terrain!
... you live in Winnipeg and any notifications after 11pm you ask are we stepping out ??
…you just pull out your laptop and a notebook and your family asks if you’re doing another mystery cache.
...you’ve shed blood to find one