"Yes, that date is obviously wrong, since Queen Victoria married Prince Albert in 1830. But that aside, I don't think this proves that "Pop Goes the Weasel" was originally a bawdy song. Isn't it likely that the author of this song borrowed the single line "Pop Goes the Weasel" from a different song that was already in common use, and used it in a suggestive manner? It's been done before (though naturally I can't come up with an example at the moment!)"

The phrase "Buddy Won't You Roll Down the Line" is a good example of what you're talking about. That's the title (and refrain) of a famous American folksong, but it almost certainly refers to older songs, probably sung by workers on chaingangs.