Throwing up em horns

A homosexual male term used in skateboarder. It implies one man giving another male an erection. When the certain male receives an erection, his 'horn' has been thrown up.

Skater- 'Hey mitch did you see that nose kickflip?"

Friend- 'Yea that was pretty hot and wicked'

Skater 2- 'You boys throwing up em horns or are you skating?