When you and your partner have sex in a car, the windows fog up. this is hot boxin. Or when you and your friends light up a [joint] and the smoke clings to the windows.\n> boy: last night i took my gal to makeout point\n> friend: oh yeah! what happend\n> boy: well we were getting hot and heavy but we had to stop\n> friend: why?\n> boy: the po-po came when the car started hot boxin\n