Need suggestions for a song to be sung by a character in a novel.

This character is American, born in 1768 and would need to have learned the song he will be singing in his childhood or early adulthood. He is exposed to merchants and seamen, so the song can be of American, English or Irish origin. It should be humerous and can be "respectably" bawdy (he's teaching it to a 16 year old boy), but it should have language which would tie it to that period. Whatever you suggest, please point me to lyrics and/or recordings.

Thanks!