Give in to the sudden urge to bend over. Bend over to tie your shoe. Bend over to prove you can touch your toes. Bend over to pick imaginary lint off the bottom of your shoe. Bending at the waist can not only hide the erection, but it can also take people’s attention to whatever you’re bending to reach. That means they’ll be looking at your shoelace instead of your crotch.
Start wearing briefs instead of boxers. If sudden, uncontrollable erections are an ongoing deal, switching to briefs will at least keep it less obvious. Briefs can help smash down your privates and keep unwanted lumps closer to your body. Baggy, clown-like pants can also help, as long as you don’t mind looking like a moron.
Pretend you are about to vomit. Suddenly becoming ill can be nearly as effective as suddenly needing to bend over to touch your toes when it comes to hiding an erection. Bent over and grab your stomach, getting extra points for un-tucking your shirt in the process, and run to the nearest bathroom or alleyway. If you remain within earshot, make audible groaning and retching noises.
Think about something twisted and sick. Twisted, sick thoughts can often turn off the erection switch by steering your brain in a non-sexual direction. Imagine someone stabbing you in the eye with a butcher knife. Think of getting hit by a street sweeper or bus. Call to mind the goriest movie you’ve recently seen. Of course, these images will not work worth a darn if you happen to get aroused by sick, twisted things.