DiscardedYKTTW Thunder Thighs YKTTW Discussion
A woman has obviously muscular upper legs.
Whether or not she is a fighter, some women have strong, muscled thighs which inspire respect. This is usually applied to combat specialists (particularly Street Fighter -esque Kick Chick types), but can be applied to any woman. Often, it can be used as a derogatory term when said by a Libby.