usually when a chick is really loose or is older. When she is wearing panties and it looks like she could be packin' some heat inside of them. When you pull the panties off and she is so loose you can squeeze both of those taco lips together and it looks like a double double.
you-"I got with this milf last night"
friend-"awesome, how was it?"
you- "it was was amazing! I will never go back to young chicks, I just love it when they have a nice big ballsack taco"