How can you tell if a boy is turned on?

Well for one, he'll get a boner. Haha.

But I've noticed when my boyfriend gets a boner, he keeps looking at himself down "there". That's happened with basiclly all my boyfriends. He also might sweaty or mix up his Words. And his eyes might not be fully open, like he's in a daze. And he might be more attached to you and be clingy at that moment. If he's shy he might walk away from you and try to get his boner down haha. Don't be offended.