What does "selling like hotcakes" mean — and why is it funny?

informal

Meaning

Selling very quickly and in large numbers.

Where it comes from

An American phrase from the 1800s. Hotcakes — griddle cakes — were a popular treat that sold fast at fairs and church events.

Why it is funny

The mild humor is how cheerfully old-fashioned it is. The newest, most modern product still gets compared to a stack of warm griddle cakes flying off a table at a country fair.

Used in a sentence

"The new sneakers are selling like hotcakes."