This is lifted from The English-to-American Dictionary, located at http://www.english2american.com/.
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crumpet n. 1. A small scone-like teacake. I’m leaving this a bit vague because I don’t know exactly why it’s different from a scone, apart from being a bit less crumbly. 2. Coming from rhyming slang for strumpet (a woman adulterer), crumpet refers to women in a similar (although a little more old-fashioned) way to totty. Suffice to say that if you were out looking for some crumpet of an evening, you wouldn’t be intending sleeping alone. In fact, you may not be intending to sleep at all. We Brits do concur with Americans on the “official” meaning of crumpet (a small savoury piece usually eaten with afternoon tea) but it would be difficult to mention it in the UK without someone at the table collapsing in fits of giggles.