Why do you say a crow flies when you tell a cold joke?

Crow is one of the primitive animals in Southeast Asia! After years of research by researchers, crows don't like hot weather! On the contrary, I like the cold climate! Southeast Asia belongs to the subtropical region! Crows don't have super flying ability like swallows and seagulls, so when people tell cold jokes, the surrounding atmosphere becomes very cold, which is exactly what crows like, so crows fly over.