Uh talk to him

. I know that sounds hard but that is pretty much the easiest way. It makes it difficult to give the "right" advice since I don't really know all of the factors that go into your dilemma, sorry.
If that is TRULY not an option? I would stand-out...ish.
1. Laugh at his jokes even if they are stupid and no one else does, but play it off

(don't passout from lack of oxygen due to hysterical, booming laughter). Play-book: he tells corny joke, you giggle (noticably but not loud), then catch yourself! look around as if you didn't want anyone to know you thought it was funny.
2. Make eye-contact. And hold it. Play-book: you look at his eyes, he looks at yours, DO NOT look away just stare for a second and smile.
3. Smile. A lot. Whenever, see him or not, just put on a grin constantly. After a while, it'll be natural and you won't have to think about it when you are around him.