It's not that I think I'm the best bass player in the world. But I don't get on a stage and claim to be anything that I'm not. I play music because I like to, not because I see it as a competition between me and some guy in a backpack with a big nose. I don't play music on a stage to prove anything. I play music because I can, and I want to, and I will, whether anyone is watching or not.
But really, what adult says that to another adult? As a person with a vagina who also happens to play an instrument, I am very much used to comments from dudes along the lines of "You guys are pretty good for being girls" or "Before I saw you play, I thought you were going to be way worse than you were." At worst, a man will have some sort of "tip" or "trick" to share with me about "how to play bass better" -- because, obviously, women are bad at a lot of stuff.
In those situations, the inherent sexism and profound rudeness is thinly veiled -- or the person barfing the words simply doesn't seem to know any better. When confronted with such passive-aggressive commentary on my playing, I'm usually quick to respond with, "Hey, since you want to show me how to play my bass, if you pull your dick out of your pants, I can show you how to give yourself a better hand job" or "I'm sorry, I didn't catch that piece of advice you gave me. Can you say it again louder so every single person in this venue can hear you?"Continue for the rest of the story.