When while having sex, one partner opens the other's buttcheeks and begins to suck on the anus. He/She sucks until the diarrhea fills the sucker's mouth. The sucker then smiles and pushes the liquid shit through his/her teeth using his/her tongue.
Bob: We had chocolate fondue.
Joe: With strawberries or marshmallows.
Bob: No silly! With diarrhea!