Exhibitionist Boy/Keep masturbating

The door swings open and your mother quickly steps into your room.

"Hey honey—"

She immediately cuts herself off and freezes in the doorway with a look of surprise on her face as she realizes what you're doing.

She hasn't seen you fully naked since you were 7 years old, and she can't prevent her eyes from dropping down automatically to the unexpected sight of your erection in your hand, much longer than she remembered it. She puts a hand partly over her mouth and stares at it in shock.

Being caught like this is humiliating, but as horny as you are, your mother's reaction is actually turning you on. In a way, this is your fantasy come true, even if you'd never wanted it to be your own mom watching you from the other side of that imaginary window in the mirror. You can't help yourself, you just keep going, stroking your cock up and down while your mother stands there watching. You figure you've been caught already anyway, might as well get the most you could out of it.