Are YOU a donut?

I had my first funny Japanese snafu in class tonight. The teacher was asking us to read out loud from the book and to interpret what we'd just read from Japanese to English.

One sentence structure we've studied alot is: "__(noun)__ desuka." Which translates to: "Are you a __(noun)__?"

Up until my turn, everyone got to fill in the blank w/ words we'd already learned. So now it's my turn to read out loud, and my sentence is: "Donata desuka." The teacher says, 'Ah, we have a new vocabulary word, "donata." What does this mean?' I tried flipping to the index to find out, but couldn't find it fast enough... It was dead silence, except for maybe some crickets chirping. The sensei urged me again: "Can you guess what this means?" So I gave it a shot: "Are you... (pause) ...a donut?"

The whole class laughed. WHAT? A lot of Japanese words are just converted English words (like hoppi owa and Amerika)! Why can't donata be donut?? Who knows what "Are you a donut?" is really a euphemism for? Those freaks buy teenage girl undies out of vending machines, for goodness' sake. How am I supposed to know what kinda freaky, deviant, breakfast pastry lines they like to use on chicks?!

So anyway.. later on, I overheard this girl a few seats down from me getting all frustrated because all she could think of when she read "donata desuka" from then on was: "Are you a donut?"