If I'm in close quarters with a bunch of other people, like at a movie theatre, I try to be discreet and polite, but when it comes to place like parking lots or parks, or driving around in my car, I try to take the biggest, most obvious puffs I can. I keep hoping someone will notice, "Hey, that guy just stuck a lit cigarette burning tip down into his shirt pocket before he walked in here!" but so far, no one seems to have noticed.