A few of mine:
-When the fish raises, gets 3-bet, then goes "how much to me?" and fumbles around trying to figure out how much more to put in to call. Wtf man. Put out the 3-bet amount and pull back ur bet. Or go back to 3rd grade math class.
-Fish looks at the clock to confirm what level it is, grabs chips to assemble raise, looks back at clock, then proceeds to make it like 6x. This whole process feels like it takes about a full minute.
I have a few more that all fall into the category of "poorly run poker rooms/terrible floor staff". That actually tilts me more than any player action.
Let's hear some!