They do, but most of the time they use 1 arm to lift the skirt to cover their crotch.
Nn... Haa... I'm really getting wet... I wanna touch it... I wanna touch it... I want to masturbate soooo bad!I... I've done it... I've completely exposed my pussy with everyone around... Come on boys, if you just turn around now, you'll see my private place on full display!