Making milk look normal / taste horrible (for fun and profit)

MetroidZoid

If H/A can't figure this out, no one can. Alternatively, no one plots like H/A can.

My fiance has discovered that someone has been drinking her milk in the break room fridge. She marked it with her initials. Still it gets drunk. She marks a line on the carton just to make sure ... and it still gets drunk. It's not so easy to say "Hey who drank this?" as this is a large fridge ... in a large breakroom ... shared by 400 people. Yeah.

So we want to make this shit-nasty but otherwise appear normal. My first thought was vinegar, but apparently via over-the-phone experiments by her aunt (long story short, we didin't have vinegar, but when she called I brought up the 'sour milk' and she tried it out) reveals that it curdles the shit outta it. Doesn't pass the visual test. Also alcohol would get my fiance in trouble, so that's out.

[x] Vinegar
[x] Alcohol

So what else? Crystal's passed the idea of using half-and-half or buttermilk. And apparently lemon juice also turns regular milk into something like buttermilk? Or does anyone else have know any other house-hold ingredients that would do the trick? Or other tricks to work in a similar office situation?

And yes, we both realize it's a little on the petty side to use such tactics, but there's no reason why my fiance shouldn't be able to keep a pint of milk in the fridge, when there's plenty of room, for her breakfast break usage, without someone 'milking the cow for free' so to speak.

Improvolone

Salt.
But really she should make the bottle look gross rather than fuck with the actual food.

Pheezer

We do not fucking do threads where the question being asked boils down to "how can I be a horribly annoying person". This is in the rules thread. Read it.