These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
While drinking one's own piss is a (flawed) survival tactic, if you're in a place with no clean fresh water, a number of pictures on Memebase among other places put him in situations where he seems to be doing it for no apparent reason at all. To wit:
"Sun's going down... better drink my own piss."
"Can't find way out of Wal-Mart. Better drink my own piss."