I enjoyed this from postdoc JesstheChemist on Twitter: "Busted. Just caught someone (who doesn't work in my lab) going through my lab drawers." Now that's a real-life lab comment if I ever saw one. It's a constant feature in academic labs, where there's usually limited equipment of one sort of another. There's less of it in industry, where we're relatively equipment-rich, but it certainly doesn't go away.
Glassware gets rummaged through, whether for that one tiny Dean-Stark trap, a funny-sized ground-glass stopper, or something as petty as a clean 25 mL round bottom. Run out of that fancy multicolor pH paper? The guy next to you keeps it in the second drawer. One-mL syringes ran out, and you need to dispense something right now? Third drawer.
I've seen people borrow things while they're in use. In grad school, I once had a short-path vacuum distillation going, with the receiving flasks cooled in a bath supported by a lab jack. I left for a few minutes while things were warming up, only to find my lab jack pilfered and replaced by a ragged stack of cork rings, which was not what I had in mind. Peeved, I hunted through the labs until I found the jack in the hood of a post-doc who was running something of his own. "I didn't think you were using it", was his response, which prompted me to ask what it looked like when I was actually using it.
Then you have reagent burgling, which is epidemic at all levels of bench chemistry. No one has everything to hand, and you always run out of things. The stockroom may be some distance away, or take too much time, or there may be only one bottle of 2-methyl bromowhatsicene in the lab (and you don't have it). This can be innocent, as in taking 500mg of some common reagent out of a large bottle that someone has handy. Or it can be more serious (but still well-intentioned), in the "I'm going to bring it right back" way. Further down the scale, you have plain nastiness, of the "I need this and screw the rest of you" kind. I told the story here of having had most of a fresh bottle of borane/THF jacked from me, and you know, that happened in 1986 and I'm still a little cheesed off about it. Many readers will have experienced similar sensations.
Once, during my grad school days, I went off on a rare vacation and left notes in the various drawers of my bench. "It's not here!" read one of them, and another advised people "Take this from (fellow student X). He has a lot more of them than I do". When I came back, people told me that they enjoyed my notes. There you have it.