This, word for word, occurred earlier tonight outside a local Friendly's.

The people involved:
--Me
--Brad (known for not being particularly tactful)
--Craig
--Craig's girlfriend Deb

An employee was outside holding the door open for customers.

Me: Thank you. (as I passed inside)
Brad: Thanks.
Deb: .....
Craig:: Thank you.

Craig (once we got inside, half-whispering to Deb): Way not to say thank you, Deb...
Deb: He's a stranger, why should I say thank you to him holding a door open for me? After all, I'm a girl.
Brad: I donno, maybe because it's simply being polite? See how far you get in life expecting things to get done for you just because you're a girl. So much for equality, I guess.

Deb got really indignant and didn't talk to Brad for the rest of the night.