A "stankle pumpkin" is a wife or girlfriend that really, really smells foul. The odor usually originates in the morning and during coitus.
(Note: stank lines may be seen rising from said stankle pumpkin's body, as if she were a cartoon)
John: I woke up this morning after having sex with my girlfriend.
John: She stunk! I mean, she wanted me to go down on that and I was like, "Nah baby, I don't go down on stankle pumpkin's."