Not the most brilliant one to date, this was kinda a rush job. But you get the hint. Or the innuendo in this case.
"Horizontal Tango" being a euphemism for...well you can work it out. XD And Cesar's causing random fits of laughter for Six by letting his dirty mind wander. Rex is wondering if Six has lost his marbles..
I love pairing those two, they're adorable!

Generator Rex (c) Man Of Action