rabbit tail
A much larger, more unkempt version of the bunny tail.
When she mooned those people, her rabbit tail wagged happily in the wind.
rabbit's tail
The completely unexpected - but most welcomed! - brief moment of witnessing a sneaky glimpse of a girl's white panties e.g. when exiting a car in a short skirt.
"Keith, Keith, did you just clock that bitch's rabbit's tail?!"