I don't have a very good tolerance for potty humor, so pretty early on we had to institute a rule that you only talked about bathroom things IN THE BATHROOM, so no running around screaming "i'm going ot FART on your FACE" in our house, at least i try, the kids are pretty good, hubby i'm still working on, lol.
As for the gifts we practice before and gift getting occasion, What do you say if someone gives you and Ipod, THank you! what do you say if some gives you a dirty sock? thank you! what do you say if someone gives you a puppy? Thank you, What do you say if someone gives you ( a boy) a bottle of perfume? what if someone gives you ( a girl) a .... I am out of ideas, we usually play until I run out of gross stuff to offer them.
I always tell them, that after they say Thank you and we go home, if a gift is inapropriate for them that I will "take care of it' my generic term for exchanging, regifting, etc etc.
There was still one time my DD said Thank you through her tears of disappointment for somethign she was given that wasn't what she wanted, can't think of what it was. but i was proud of her for trying.
and this mama would NOT put up with asking for gifts and acting greedy.