This happens a lot!! I work at a spa as a massagist and waxing people bodies. Guys are always flashing their dicks and remove their towels. If not, they have a boner 99% of the time. And when it comes to waxing, 70% of my clients are men so I get to see and grab their dick and balls. Some of them cum all of a sudden. Luckily, I love all this and I love my job