I think one of the worst was last year. I work at a ski shop (sometimes by myself during the day when it's really slow) and during one of these times I was waxing some skis and this guy comes it. So I go up to the counter, ask him what he needs..
Guy looks at me for a good ten seconds, judgmentally none the less, and then asks,
"Is there anyone else here?"
Me: "No, I'm the only one working right now, is there anything I can help you with?"
Him: "Are you sure? I want someone who actually knows what they're doing."
Me: "I've been working here for a while, I'm sure we can work it out."
Skeptically: "Well alright then."
Sometimes being the only woman in the ski shop is rough.