- I enthusiastically say "Hej hej!" to baristas and the like, then quickly switch to English when they logically attempt to converse with me in Swedish.
- The way to authorize my credit card for international transactions changes daily (not really, but I never remember how), so I end up telling cashiers to do the wrong thing when I want to buy a train ticket or something.
- Whenever I have coffee, I accidentally dribble it out of my cup and onto the table. Even though I sop it up in a semi-timely manner, it leaves stains because Swedish coffee is made with black bleach.*
- Sometimes, I babble a weird mix of Swedish, German, and Spanish and get irrationally annoyed when no one understands.
- Being loud. It's not intentional. It just happens.
Disclaimer: I'm sure these things bother more than just Scandinavians.
*That's not true. But it's strong stuff.