The hungarian abbreviation of "kys" - "kill yourself".
ö - "öld"
m - "meg"
m - "magad"
The first two words ("öld meg") means kill, the third word ("magad") means yourself.
The hungarian enemy in my League of Legends game told me "ömm" on the chat, after I killed him / her.
to ingest at a very high rate, only to spiteverything out at once in a highly charged attack
person 1: omm nomm nomm
person 2: uh oh....he's doing it again...
person 1: BLÄÄÄÄÄÄÄHHHH!!!
person 2: oh grease, you just got omm nomm on me, you're such a face.