Not my vomit, but I might have engineered it a bit...
I'd been going out with a girl at uni and it had all seemed rather serious. However, things unravelled over the Easter holiday and when we got back to uni, I found she was going out with my friend instead.
Now, I'm not usually the type for big grudges, despite being rather unhappy about the situation. After a few weeks, everything seemed fine between the three of us and my friend and I went out for a few drinks at one of the hall bars (Stoneham, if you went to Southampton Uni). After a few beers, we decided to go for a spot of shot-downing. This particular bar had a very-well stocked set of shelves at the back for this sort of thing.
Everything's going well by the fifth shot, but then my friend buys a round of whiskey. Whisky is one of those things I can't abide and just the smell of it can make me gag when sober and my friend knew this, but I couldn't lose face at this stage of the proceedings.
The whiskey went down and luckily stayed down, but war had been declared.
A couple of drinks later, I could see my friend was getting a litte frayed round the edges. He got in a pair of flaming Drambuies and proceeded to burn his had putting it out. While he was cursing, I put mine out with my wallet. Once that had been negotiated, we moved onto a few more innocuous spirits.
However, after each shot, he was starting to go a bit still, holding on to the bar with a fixed expression, staring into space. Each new shot was producing a longer pause like this and I could see he was close to parking the vomit bus on the floor. Last orders was rung and I decided to deliver the killing blow. There was a drink that affected him in the same way as whiskey did to me. Triple Sec.
Two of these are promptly ordered. Mine went down the hatch. My friend only noticed what it was half-way down and spent a full minute fighting the colourful inner demons that wanted to erupt into the world. Somehow, somehow, it stayed down.
As we walked back, I could see that he was in a bad way. Perambulation was almost gone and the slurring of his words was akin to a stroke victim. As we approached the halls, I could see his new girlfriend's bedroom light was on. Time for the final stroke of cruelty.
"Hey, she's still up, why don't you go up and see her?"
"Shash, shash a good idea, Borish."
Ten minutes later, having just settled into bed, my phone rings.
"Hello?"
"What the bloody hell have you done to him? He's just thrown up all over my bed!"

After that everything was fine. Several years later, he was best man at my wedding.
( Colonel Boris "...a desperate Buzzfeed imitation...", Sat 9 Jan 2010, 6:26, Reply)