A note to anyone going to see Louis C.K. in London next week: don't heckle him. Even in a complimentary way.
Why not? Well, we think the video above - from a recent gig at the New York City Center - shows you why not.
Watch how he tackles a woman in the audience who shouts out "I think your boots are really sexy!" - and explains to her, in typically biting-yet-eloquent Louis C.K. fashion, why it's really not OK for her to do such a thing.
So, yes: Londoners, take note. Not that you would behave like this, of course. Because if you're going to see Louis C.K., you're clearly a person of great taste and intelligence.