Guy always butts in on conversations?

[Anonymous]

Hi. So, there's this guy I go to school with. Him and I don't talk that much. He stares a bit but that's all. Lately he's been listening in whenever I have a conversation with a guy and joining in. I don't have a problem with this, it's just odd because you can tell he's eavesdropping- he was dead asleep in math and when I talked to another guy about a dumb test he butted in. Then I was giving my other guy friend shit about drinking so much energy drinks and other crap, just reaping on him, and this guy joins in out of nowhere. The thing is he only does it to me and we don't talk barely at all. Any explanations? Thanks in advance!

[Curmudgeon]

He is interested in you? If you feel the same, welcome him. If not, politely take him aside and let him down easy.