Not really a stereotype, but people tend to assume I speak some Asian language because I happen to be Asian. (My parents are Chinese, but I was born in Canada.)

Interestingly, it annoys me more when the Asians make the assumption, because it's often in the context of them trying to talk to me about something and me just looking dumb. Once time I mistook a market employee for a food kiosk server (long story) and asked her for a beverage from the fridge behind her. She kind of snapped back at me in Chinese, and since I can't understand Chinese, I just stood there confused. Then another lady nearby snaps out a translation, indicating that I should go get the drink myself. Then they proceed to talk to each other in Chinese, clearly about me, while I'm standing right there. To this day, I want to punch them.