Masterbation with the lights off.
Tim: I'm all about saving the planet, I even have Eco Wanks.
Mike: What the hell is that?!
Tim: Oh I just masterbate with the lights off.
Mike: Get away from me.
Having a tug while listening to erotic noises coming from your housemates bedroom.
I had an Eco Wank last night while Vitu was banging is bird.