Raindeer is a condition of the ass made known by Nelly's song "Tailfeather". If a girl has an unusually large ass it is said that her mother must have had raindeer. Makes no sense I know but its tru.
"Is that your ass or does your momma have raindeer?"
a horse like shaped animal that parents make little kids bealive in and are ridden by Santa Clause.
"Hey mom look, I think daddy's being attacked by a raindeer!"