Why is my "friend" so weird?

[Bob Saget]

Alright I have this small group of friends that I usually hang out with at school and they're all pretty cool except for this one kid that kind of hangs out with us without us really wanting him to. I've know him since kindergarten but for the past 2 years, especially this year, he's been really creepy. He rarely showers, and he'll just sit there and stare at peoples clevage, and I swear if we were like cutting our own feet off, he would do it too, he just does whatever he thinks we thinks is cool. And hes really creepy to girls he likes. Like he'll repeatedly ask them out and he just never picks up hat they don't like him. He sent someone he likes a text asking "if it was just him or has your sisters boobs really grown?" then he kept testing her sister and she told him to fuck off, and he said "yes, fuck me hard". He takes depression medication and one time I caught him looking at porn on my computer... He's 15, I'm 14.