What did Spock encounter in the Enterprise toilet?
The Captain's Log.
The Captain's Log
Explanation
Explain Bear
Listen up, buttercup. You see, the "Captain's Log" is the official record of what happens on the Starship Enterprise, right? And a "log" can also mean a piece of poop. So, Spock found a poop in the toilet. It's funny because of the double meaning. Now, go back to watching your cartoons, you cotton-headed ninny muggins.