It's quite funny how something which is no fault of your own is potentially the most embarrassing thing to happen of all...
This happened to me once recently, but very luckily it was very early on Sunday morning and I was only a couple of minutes from my house...

i've actually had this happen to me before, and was pretty embarrassing. i was not a fan of birds for quite sometime.

I took a first date one time to the Natonal Zoo in DC. While looking at the laughing hyenas, I felt a little plop on my hair. I bent over and the girl started laughing because I had bird crap in my hair. I had to walk to the bathroom and wash my hair out in the sink with some paper towels. No worries though...the bird crap must have been good luck, cause the girl became my wife.

How embarrassing.

9:45am on a sunny Thursday morning, I step outside Starbucks, look up, and see this real big amount of bird crap coming down. I dodge, but this tourist next to me is taking pictures of something stupid and it makes it all in her hair, down her hand and on her digital camera. At first she didn't really say anything, said What the f I would imagine in some foreign language. I was cracking up. Then she says more stuff to her husband or whatever, probably choice words about me, but in this situation the bird has the last laugh. She's gotta go back to her hotel, change her outfit, be upset all day on her vacation, etc. Hopefully she was very far from her hotel.