Nicky is a total slut who loves sucking cock, and Joe gets off on seeing his husband suck other men.

The love going to local glory holes, where Nicky gets on his knees and sucks any cock that comes through the hole, and Joe is with him, murmuring about how much of a cock-hungry slut he married. (Not in a derogatory way, more in a 'I love this about you' way.)