I didn’t experience this until i was an adult and it was a true What The Fuck moment. It’s absolutely sexual assault. The guy did it a second time and i realized the only socially acceptable way to get him to stop was to do it back to him but with a really really strong punch. That worked, but i didn’t want to touch his dick any more than i wanted him to touch mine, so i shouldn’t have had to do that just to protect myself from an unwanted physical attack on my genitals