A milliesexual is someone that would totally smash Millie Bobby Brown regardless of sexual orientation. Doesn't matter if they are gay, straight or trans, they get totally hard at the thought of Millie Bobby Brown.
Me: OMG I totally wanna smash Millie Bobby Brown. Friend: I thought you were gay. Me: I'm a milliesexual
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"