Always liked that one, too.

I once went to a restaurant with a friend. My friend ordered a root beer, then the waitress turned to me and asked what I would like. I said "I'll have a root beer, also." The waitress nodded, wrote that down, and walked away.

It soon became clear that something had gone awry; our sodas didn't come and the waitress could be seen walking around the back of the restaurant asking other staff something. Finally, the waitress sent out the (very pregnant, I felt bad that she had to walk out) bartender to tell me that she was sorry, but she'd never heard of a "root beer alto" and so wasn't sure how to make it.

I always found that a bit embarrassing. I tend to use "also" instead of "too" because I find it less ambiguous and also because I have pedantic friends who, if I had said "I'll have a root beer, too" would say things like "root beer 1 not good enough for you?" My intent was to be more clear, not less! That's the only time it's backfired for me, though.