I think my worst was probably when I was told I could play a tiefling while building the character with my DM. It wasn't until after the fact that I was told that I don't get any of my racial abilities. This wouldn't have irked me as much if it weren't for the fact that the aasimar player was allowed all of their racial traits, and the bug man (I forget the name of the race but it was 3.5 DND) also got his stuff which included wielding 4 weapons at once. I stuck around because it was the only table top game I had locally available, but it was weird not getting to do stuff like other players. I tried asking a couple times why I can't have my racial powers, and the other players just told me it's the DMs decision and to just drop it.