There are some places you just have to pee in a cup. This is one of those places. Some will find this one quickly, while others will take some extra time. BYOP.
Please place the container carefully back how you found it. so that it will be there for the next searcher.
PLEASE NOTE: Signing the physical log sheet in the cache is part of the game.
Congrats to Goin' PostNet for the FTF.