1) You're easily confused by coins
You’re too paralyzed by fear to figure out the complex mathematical worth of shrapnel when it comes time to pay, so you present the cashier with open palms bearing all of your coins, and a plaintive look, communicating "Please, take what you need -- I'm at your mercy".
2) Gratuity-happy is your middle name
Waiters scramble to serve you once they hear your accent -- because they know you'll automatically throw 'em an extra 20%, even though they get paid more than you do and tipping isn't a part of the local culture.
3) You're not, actually, smarter than a 5th grader
The Alps are in Sweden, right? Austria is the one with the kangaroos? Hitler Youth... that’s still a thing here?