Something similar. I worked at golf driving range and a customer approached to buy a bucket. I said "What can I get for you ma'am?" He was an old guy with big man boobs. Ouch. I gave him the bucket for free.
Yes, I have said sir and ma'ma to the wrong gender more than once. Usually I catch it and correct very quickly. I have never had any customer throw a fit.
No, but I've accidentally mistook a man for a woman and called him "ma'am" He looked like a little punk chick, sorry.. Anyway, I get mistaken for a "sir" all the time because I guess the short hair and not very bulbous chest throws people off. Usually my mega girly voice is a give away, it's disgustingly sweet. I hate it so much.