Styvmamma bästa vän

I let my girlfriend drop off her 19 year old stepson at my place while she takes a vacation, she just doesn't want her house over run with tramp girlfriends, screwing etc while she's gone, I said sure he can stay here. But i accidentally walked in on him, he was practically naked laying on the bed watching porn on his laptop , being more curious I asked what he was watching and he showed me as his very nice big hard cock popped out