They always ask stupidly technical questions that i get stuck on or just plain don't know. How exactly does my performance on a 10-60 minute pop quiz relate to my ability to complete the tasks i'd actually be assigned? You'd think 4+ years of experience in the industry would count for more than it seems to.
It's a bit nicer when they actually ask about what you worked on before in details of more than one word, or when they ask for code samples.
And i hate it when they ask you if you have any questions at the end. Do they penalize you if you can't think of any?