When an old guy brings his grandchildren to the post office or bank (or anywhere else only old people like to go) and locks them in the car, leaving a dank old person fart behind.
Also works with rotten cabbage locked in the trunk during a hot Minnesota summer.
Grandchild 1: "ewww... what's that smell?"
Grandchild 2: "I dunno, grandpa must have farted before he locked the car! GROSS!"
Grandchild 1: "Ah, he gave us the old Iverson Special."
Grandpa: "Take that Johnny son-of-a-bitch!"
Prices shown in USD.