This thread has awakened some nearly-forgotten memories from almost a half-century ago when kids used to sing this on the streets of Brooklyn. I can't remember all the verses I heard, but here are a random few to add to this wonderful scholarship:

What's that thing between your legs? (3x)
Said the fair young maiden

It's just a pole to shove up yer hole said Barnacle Bill the sailor (2x)

What's that running down my thighs? (3x)
Said the fair young maiden

Holy Smoke, me scumbag broke said Barnacle Bill the sailor (2x)

What if I should have a child? (3x)
Said the fair young maiden

I'll dig a ditch and bury the bitch said Barnacle Bill the sailor (2x)

What if they throw us in jail? (3x)
Said the fair young maiden

I'll use my cock and pick the lock said Barnacle Bill the Sailor (2x)

or:

I'll swing my balls and shatter the walls said Barnacle Bill the sailor (2x)

I seem to remember the last two responses sometimes were combined into one answer, with neither line being repeated.