When I was in one... it wasn't that hard. Could just fap, or do what the others said, involving different sexual activities.
Also, on one of Jorick's points; I never did that. For the most part, I don't even talk about whoever I happen to be dating, local or long distance. But that shit is annoying. A girl told me the other night she loved me... after talking to me for a few days and knowing next to nothing(She said she 'knew enough').