A hotdog that has been cooked in a microwave until it splits down the middle. The center is then filled with mustard, mayonaise or your favorite sauce.
We were going to roast some wienies, but since we had no matches and no buns we decided to pop them into the microwave and make vagina-dogs.
It's when you put your weiner in a girl but hot dog wise. So like, she's laying on the ground, and your dick is parallel to the ground, and her vagina lips are around your weiner.
Oh man, I totally did her, Hot Dog Vagina. My dick was totally in her vagina, hot dog wise.