Vom is Short for Vomit
Vom means throw-up, regurgtation, barf, ralph-- stuff that was in your belly, but that then came out after some digestion.
• Oh my God, there's vom all over your kitchen from how drunk I was last night.
• Oh my God, I have to vom. I suddenly want to ruin your kitchen.
• Hey nice kitchen, awesome that we get to get drunk in it.