Friends want to wear lingerie Halloween costumes

So the situation is… my two friends(F 26 & 25) are wanting to dress up for Halloween in a certain theme. The only issue is the costumes they’ve picked come from fashion nova and are really skimpy. They’re even pushing the issue of everyone butt has to be out so we’ll look uniform. I’m not comfortable wearing these lingerie costumes especially considering that I have a boyfriend and that’s not a look I want to portray in public. AITAH for not agreeing to wear these costumes and suggesting alternatives like making our own costumes?