What to say/ do/act like if a guy whos popular jokes around and says i love you and stuff bt its a joke?

theres this guy who used 2 kinda lke me and he mite do this with most of the guys in my 7th gr cl cuz we r kinda lke this...immature. hes says wierdish and jokey stuff lke i love you wen i go offline on aim a. what do i do/ say after he says this?