In the past 5 years, I've been noticing I've been getting erections a lot more often. I learned in health class that this is because I have entered puberty and am thinking of girls, thier bodies, and what to do to them. Sometimes my erections would bulge out of my shorts looking embarrassing. I found that if you go to the bathroom, pull out your hard on, put it so the head and some below is sticking out above your pants line. This gives the illusion that you do no have an erection, and it will go down quicker.
I find this helful in situtations where I don't want an erection, sush as school.