That is the thing, Magic has rules, self-expression be damned. Consult your Head Judge.
Ugh I remember this guy I faced who had bikini girl sleeves he was so gross
Card sleeves are technically illegal in any case, ain’t they?
Card sleeves have to be opaque and uniform. I think they also have to be simple (no complex designs), but that’s up to your judge too.
DCI Judge here,
Generally, the rules for card sleeves are that the sleeves have to be opaque, non-reflective, and all have identical designs (or lack thereof) and a solid-colored border. Sleeves meeting this criteria, and that are not objectionable for reasons of wear or content, should be acceptable at regular and competitive RELs.
As for the person disgusted by the bikini girl sleeves, I have good news for you, and for everyone creeped out by those sleeves. If you find any content a person brings to a tournament, whether it’s sleeves, a playmat, their T-shirt, or a card alteration, at all objectionable, talk to a judge. If a person’s behavior makes you uncomfortable at a tournament, talk to a judge. The person will be asked to change their behavior, or replace the objectionable item with something less objectionable, or if that’s not feasible, will be asked to do without the item. It is our job to make sure everyone at an event is comfortable with their surroundings, and to allow no person at any event to jeopardize that.