Random ***** problem?

So lately I've been having random s, I know it sounds like I'm a pervert. But I swear it's not my fault! I'm not even thinking about nasty things. Like whenever I wake up... it's just there starring at me, and it won't go down. The other day I fell asleep in cl while the teacher was giving a lecture and naturally he called on me. It was so hard and I was wearing basketball shorts... It kinda looked like a third leg. I needed time for it to go down so just kept saying "huh?, huh?, huh?",like if I couldn't hear him (I looked very dumb). But the teacher just kept calling on me, so I got up and started walking from side to side, kinda like a penguin, while bending over. And when I got to the board, I just pushed my crotch against the wall (it looked like I was it). And then I did the same thing when I walked back to my seat. My friend asked me "why were you walking like a retard?", and I said I was falling. I looked very dumb, how can I prevent this from happening is there like relaxation technique? I already tried slapping it, but it just gets worse. I also tried putting it under the waistband, but the "head", pops out. And if I put my shorts any higher I'll look like a retard again. Any tips? How do you guys make it obey? This is very embarring for me so please no rude comments.