Occasionally; what I hate most is running into somebody again after you've already just said goodbye to them.
Like at work: you go into the breakroom to get a coffee, see some coworker you know slightly, engage in some obligatory polite conversation with them ("Hi, how's it going, what are you doing this weekend, oh really? Well, have fun. See you later.")
Then, five minutes later, you come out of a bathroom stall and see them standing there at the sink.
It's such an awkward situation. It's like, should I say hi all over again? Should I just ignore them? Are they going to think I'm stalking them, being rude, being over-friendly? What the heck am I supposed to do? How do normal people cope with this type of situation?
So yeah, I avoid this type of thing at all costs- running into the same person over and over again- even if I have to avoid rooms where I suspect they'll be.