I drive this route often when I go to visit my sister in Riverside. On my way home from a recent visit I noticed the lack of caches in the area. Then an idea hit me--hide a cache and start a series!
This is the first of hopefully many caches of my Knock Knock series. Use the Knock Knock joke for a possible clue. Think of it as a hidden hint and enjoy having to read some corny Knock knock jokes. 
Knock Knock.
Who's there?
Oily.
Oily who?
The oily bird catches the FTF worm!!