Honestly, it doesn't actually have to be real violence. There was a trend a couple years ago of girlfriends play-wrestling with their boyfriends, and asking their boyfriends to actually use all their physical strength. The results were unsurprising to everyone but women. Hell, just a bit of mildly rough sex would probably be enough for most relationships.

Sean Connery was right about women. Not just the "slap" part, but the part that came after specifically.