not much, really depends on how much pee, if its alot it will mess up your engine, if its just a little then it wont do anything, I recommend a fuel stabilizer immediately and letting your viehicle run for around a half an hour. Urine is ammonia based and will burn though your engine on most occations. Also, pick up a locking gas cap, if someone pees in your gas tank they obviously want to do damage and if they are presistent its only a matter of time before they fnd out what sugar can do. (picture ooey gooey carmel popcorn in your engine, can you say INSTANT seizure?) Best of luck.
pancake sryup is my gas tank, what do i do?
the tank will leak
What happens when chicken bone gets stuck in gas tank
pancake sryup is my gas tank, what do i do?
You will likely need to drain the gas tank.
pee in the gas tank impoes youe GPM
remove the fuel tank and drain the water
Nothing
You'll have infinite gas and live forever.
Nothing.
melt
NOTHING