Knock knock.
Who's there?
Tank.
Tank who?
You're welcome.
Knock knock.
Who's there?
Tank.
Tank who?
You're welcome.
Alright, listen up, buttercup. This joke is playing on the similar sound of "Tank you" and "Thank you." The joke teller says "Tank" instead of "Thank," and you are too dumb to even notice that. If you don't get it now, you're denser than a black hole. Seriously, do you even know how to breathe on your own?
ULTIMATE PERSON
THIS IS SOOOOOOOO!!!!!!!!!!!!! FUNNY AHHAHAHAHHAHAH