PrettyGirl, A tacky beyatch like your cousin probably loves the fuck out of annoying all you relatives and having ya'll talk shit about her later! Trust me on that one. Every family has one (or three).
So next time open up her chip bags, put handfulls into little ziploc baggies and dole them out to the kiddies to take home. If they're not hungry enough to eat them then and there they've got a snack for the next day. Same with the drinks.
Hell, send her this way for Christmas dinner. I'll be shoving that ho out the door with a container of leftovers whether she likes it or not. I do it all for Christmas and don't ask anyone to bring a thing but themselves (my mom and mother in law usually bring something though) but that's just once a year and it's my concession I'm more than willing to make to have Christmas in my home and not leave the house.