Clingy Friend

Okay I really need help, one of my friends really likes me and we talked for  a while but he went and asked one of my really good friends for nudes after he had told me he liked me and I told him I wasn't sure how I felt... he makes me laugh but he always makes inappropriate jokes and flirts with me even though I friend zoned him... idk what to do because I keep telling him we're just friends but he's being clingy and pushy and I don't like that, but I also have a class with him for 3 more weeks and I don't want to make things awkward because he sits right beside me... help please