How to Be An Ugly American

Tonight, some woman got annoyed with me when I mixed my coffees together in the cafeteria.  This prompted me to wonder what other things I do to inadvertently bother the people here.  After a little reflection, I came up with this by all means non-all-inclusive list:

• 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.