When you are engaged in anal sex with a girl (or guy) and you ejaculate into your partners asshole (creampie) you take a straw and stick it in your partners anus and suck the sperm out.
Montez: "mmm..i cant wait till after school so i can stalk chad home and watch him in the shower then brutally rape him and give him a good ole slushee!"
Thomas was shocked there were no napkins at the bad Sushi restaurant, but his messy sushi slushee afterward had him horrified that there was no toilet paper.