Look at it this way, if girls don't even like him touching their forehead(s) (for whatever reason he wanted to in the first place), then chances of getting laid are probably extremely low, so, generally through out life we'll still have opprotunities to torcher him.
Secondly, Joe, how is that sexual assault? And if she's "friend-ish" with you, why would she call the cops? I've done things a lot worse then poking their forehead and it hasn't been sexual assault.
Lastly, why the hell do you want to touch her forehead?