first example: buying stuff for colleagues when you pop out to the shop at lunch. annoying things:
- when you agree to get something for one person and someone else is like "oh are you going to M&S? Can I have...?"
- when they don't stock the requested item and you have to make the call to see if there's a suitable alternative (or risk coming back emptyhanded)
- when the change you have in your pocket isn't the right change you need to give to your colleague, and so they have to give you change back from your change.

of course, all this could be avoided by not agreeing to buy stuff in the first place