Homma is short for Homosexual. It is used to hang shit on some one who is pissing you off or acting like a girl. It is used insted of "homo"
Matt says: I dont feel like drinking beers again tonight, i know im a bit of a skirt.
Adam says: Dont be a god dam homma, gees your a pussy!
Matt says: But we have been on the beers all week, cant i have a night off to recover?
Adam says: Shut up homma