Need to remember that people should be taken literally sometimes. I met some new people and was on my way to a party when the girl who invited me said "this is my daughter." Her 'daughter' was around 18 and she was around 35 so I figured they were just really good friends and 'daughter' was the cute term employed to help people overlook the age difference.

My mistake.

I eventually had to say, "wait a second, by daughter, you mean, she's your daughter?"

It actually went over quite well.