When Amy and Bender hooked up, or Fry and his Lucy Liu-bot, and other human-robot couples, how exactly does the sex part work? Do robots have sexual organs? Do they feel pleasure in a way that's comparable to humans?
Hahahaha, that takes abstraction to a new level.
I suppose the best description would be "kinky".
But then who knows.
I think Futurama goes for the laughs. When Bender brings home the prostitutes, you hear the sounds of machinery backing up and drilling. When he hooks up with the ship, I think he used cables or something to "mate" with the ship.
People have "fun" with machinery all the time (the internet is a dangerous place). I'm sure if a robot and a human want to have some fun, they'll workout the problems.