A buckle bunny is a female fan of rodeo

Rodeo

Rodeo is a competitive sport which arose out of the working practices of cattle herding in Spain, Mexico, and later the United States, Canada, South America and Australia. It was based on the skills required of the working vaqueros and later, cowboys, in what today is the western United States,...

 who purposefully seeks encounters with contestants who have proven successful in their events. The term comes from a slang term for women ("bunnies") and the belt buckle

Belt buckle

A belt buckle is a buckle, a clasp for fastening two ends, as of straps or a belt, in which a device attached to one of the ends is fitted or coupled to the other. The word enters Middle English via Old French and the Latin buccula or "cheek-strap," as for a helmet...

s that are awarded to the winners in rodeo.

Buckle bunnies are a particular kind of groupie

Groupie

A groupie is a person who seeks emotional and sexual intimacy with a musician or other celebrity. "Groupie" is derived from group in reference to a musical group, but the word is also used in a more general sense, especially in casual conversation....

. They offer the cowboys many things: a place to sleep, a lift to the rodeo, or sometimes just sex

Sexual intercourse

Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

. Bunnies "usually do not expect anything more than sex from the rodeo participants and vice versa".