The papers of collectors like Thorp, Lomax, Dobie and Randolph must contain unexpurgated versions of many such songs, but one would have to check them out in the corresponding repositories. Randolph at least has published unexpurgated versions of some songs, and you can also check Logsdon's The Whorehouse Bells Were Ringing. I'm not trying to score points in drinking bouts with rugby players, so I don't seek out songs with gratuitous crudity.

Or you could do what the cowboys did: dream up your own verses. Couldn't be any worse, doesn't take much imagination, and you wouldn't be far off from collected versions, from the samplings I've seen.