Excuse Me, Did you Just Fart?

I met a 5 year old boy last night. Very chubby, talkative and cheeky. He was watching one of the kids channels (ahem) and he farted. So I asked him did he just fart? Without looking at me he said, "no, that was the motorbike..." and when I asked him about the smell, he said " Auntie Z... that was the SMOKE!" I burst out laughing!

I wonder as a parent, how do you react to that?!