Looking for a saw, adage, whatever that doesn’t have poop in it to signify the same lesson. “Don’t dip your pen in the company ink” was suggested by a friend, but I think that has a different connotation.
Don’t bite the hand that feeds you.
Don’t foul your own nest.
Don’t shoot holes in your own boat.
Don’t kill ur own d00dz.
Depends on what you’re trying to say, exactly, as the variety offered by Diogenes suggests.
The slightly more polite version is the “hamburger rule:” don’t get your meat at the same place you get your bread.
ETA: Actually, that one has the same connotation as the “company ink” adage, so that might not be what your looking for.
“Don’t excrete fecal matter where you eat”?
Ahem.
“Don’t excrete fecal matter where you digest nutritions.”
Another one I like is “don’t get your honey where you get your money”. Which actually was the only place I ever got my honey but it worked out OK.
There’s also “don’t pee in the pool” and the colorful but now arcane “don’t wrestle a pig in its own wallow.”
Depending on what you’re trying to say, there’s always “people in glass houses shouldn’t throw stones.”
Don’t dookie where you cookie.
I’ve said “You’re making the bed you’re going to lie in” as a way of giving the same kind of warning.
“Don’t build the latrine upstream of the mess.”
Pigs don’t wallow in the trough.
Don’t poop in your own mouth.
Oh, wait. That’s even worse.
It’s an ill bird that fouls its own nest.
A classic, but there’s that poop again!
Don’t cut off your nose to spite your face
Dissidents will be shot.
Close, but maybe not close enough.
Dont poo wer u nom
No fishing off the company pier.
No love for “Dont mix business with pleasure”?
Don’t eat asparagus for the drug test.