Peeing...

This is a good one for guys (uh, not for girls coz we're standing when we do it.. haha):

"Don't pee against the wind."

Meaning for everything you do, do it wisely. Don't do stupid thing. Don't dig a hole for others and eventually you have to jump in yourself. Same as peeing against the wind.

I mean what I meant. If you get what I mean.