Every guy has been in this situation before: For whatever reason you have a boner at a time and place in which it is inappropriate and/or extremely embarrassing to have one and you need to get flaccid FAST. What image do you run through your head to exterminate your erection? Those without a penis may feel free to answer this question figuratively.
A few years ago I accidentally walked in on my grandmother while she was getting into the shower. Considering she was like 76 at the time, it was NOT a pretty sight to see. Ever since then, I've used the mental image of her old, saggy grandma titties to turn me off instantly.
Updated by furballs dc