mac's hypothesis - Mac's hypothesis is the idea that a man can tell if he's str

Mac's hypothesis is the idea that a man can tell if he's straight or gay by watching gay porn and seeing if he gets a hard-on.

I watched gay porn and got a hard-on. I'm not straight anymore. I'm a gay man.

I watched gay porn and didn't get a hard-on. I'm still straight, but I'm a bit weird.

My brother watched gay porn, got a hard-on, and now he's in a gay crisis.