When a guy watches more of his girlfriend's TV shows, he's cutting out negotiation talk. This also eliminates having to explain the premise of his show, who the characters are, why they hate each other, and why that one guy can control people's minds. Let's just watch Long Island Medium instead, OK?!
Every one-liner is followed by an extended hand for a fist bump
Most men have an immature or juvenile side that we tamp down (with varying levels of success) either because we want the women in our lives to respect us, or simply because it annoys the crap out of them. Once things are in doubt, a man's "best behavior" tends to show a few cracks in the foundation and he feels totally OK making juvenile jokes.
There's a fine line here. Even when he's not happy in the relationship, only a true jerk will say things that hurt his girlfriend's feelings. But even a nice guy might find that some of the jokes he'd normally save for his friends start finding their way into his girlfriend time. For instance, you might be listening to "Pulling Mussels (From the Shell)" by Squeeze one day, and he keeps giggling whenever they sing the line about the "motorboat." And "squeeze," for that matter.