What's something "small* that makes you upset?

Something small that tends to really upset me is when I share my drink with someone and they drink more than I want them to.

A more specific example is if I share my starbucks drink with my boyfriend and he drinks up all of the good melted part of the drink and I have to wait to get that back. I get really upset that he steals that mouth feel away from me.

I don't want to get as upset about it as I do, but it really dampens my mood if he forgets and does it.