It isn't really my birthday. (That's not until next month, if anyone's keeping track.) But I was recently reminded of a phrase in English that's even harder to deal with in Japanese. It's a seemingly innocent question:
"What is your birthday?"
As a phrase, it's a little off from what we'd normally use. It doesn't sound 100% natural. I'd expect people to ask 'when' my birthday is rather than 'what'. The interesting thing is, if you sound it out, it's pretty similar to:
"私をぶって" (watashi wo butte)
...which means 'hit me'. This complete verbal coincidence is beautifully demonstrated in the following video.
I for one have never forgotten the potential for this one question to go wrong. Be very careful when trying to determine someone's age, or they might count it out in bruises on your arms.