I'm more wondering how the general subject of gender bending got narrowed into ugly guys (a bit redundant...) modeling female clothing. This is way funnier.
Backstory: Ranma was (martial arts) cheerleading one of the kendo competitors (who is actually the girl Ranma actually loves but can't admit it). In a desperate attempt to raise the morale of the nearly defeated competitor...
In all of the universe there is only one person with your exact charateristics. Just like there is only one person with everybody else's characteristics. Effectively, your uniqueness makes you pretty average.