Sentence:  I mean, the urge to <WSD>yiff</WSD> is a pretty weird thing to admit to. Not something you can just drop into conversation. But look at them, hundreds of them, all gathered together in a Vegas hotel, exchanging information and experiences, the knowledge of their rare urges ever growing. 
Meaning of the word marked with <WSD> tags:  To have sex, to mate (said of animals, especially foxes, or people dressed up as animals).