Unfortunately for the spectator it didn't look like Cav was enquiring whether he was having a good day or enjoying the spectacle of the Tour of Britain, but more like the rider was berating him for doing something wrong.
The television coverage didn't catch what it was the chap did to evoke the reaction from Cavendish - some media outlets and people on social media are saying that he was holding a selfie stick, but on the video it looks like a small flag.
Whatever he did, he was looking awfully sheepish when Cavendish was 'having words' with him, so he'll probably not do it again at a cycling race for a while.
The Tour of Britain continues on Tuesday with a stage between Congleton and Tatton Park.
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