Goes like the clappers

My husband, who grew up in London, England, used the phrase "goes like the clappers" the other day. I grew up in New York, have lived in Chicago and San Francisco, and have traveled all over the US. That phrase was a new one on me!

We started looking for the origin of it, and there are several colorful theories. Michael Quinion writes about it being RAF slang, there is a theory about English schoolboys ringing bells, one about hell's bells, and another about rabbits and something to do with French. I wonder, Grant or Martha, if you can tell us what those clappers really are.