If he really pisses you off... Wanna know a cool trick that he can't do to you? It hurts like hell for most guys. It might not work on him though... (And parents can't tell you off because you're not kicking him in between the legs.)
Press his thumb forwards. Making sure the joint bends. Hurts like hell for guys (toes work too, the big toe) but doesn't affect girls at all.
Yeah, my teacher did it to a couple guys in my class. Only one didn't get affected. Twas hilarious. She does it on her husband all the time apparently.
:/
Still not getting anything. Probably because my thumbs are 'double-jointed.' Conceptually, the pressure thing will work on any joint that isn't as loose...like if you try and begin to bend your hand down toward your forearm.