Tell him it's time for you to go home.

You realize that the top of the parking garage isn't the ideal place for a liaison, and you suddenly have second thoughts. You're still horny as hell, but you just got cold feet a little. You put a hand on Isaac's arm, 'I'm sorry, I actually need to head home now.' You can tell he's caught off guard, but he smiles good-naturedly and stands up. You feel a little bad and maybe it's the **** or the pot, but you decide to give him something. You slip off your thong and hand it to him. That will be a fun mystery for my husband you think. Isaac offers you a ride home, but you know he's high and it's a pretty easy decision for you.