Some fruits of "Merrily We Roll Along" research:

1. A college parody:

MERRILY WE ROLL THE KEG
Found in several places, including Songs for Swinging Housemothers (1961) and the Beer Bust Songbook (1963). I've found no occurrence previous to 1961.

Merrily we roll the keg, roll the keg, roll the keg,
Merrily we roll the keg across the barroom floor,

Tweedlidee we drink it down, drink it down, drink it down,
Tweedlidee we drink it down, until there is no more,

(Slow) Sadly roll it back again, back again, back again,
Sadly roll it back again, because there is no more.

2. A sea shanty:

GOODNIGHT, LADIES
Alternative title, Merrily We Roll Along
From Hugill, Shanties From the Seven Seas, 2ed, Routledge, 1980, p 179.

This is the way we sew the sails! sew the sails! sew the sails!
This is the way we sew the sails on the good ship Shenandoah.

This is the way we heave the lead ....

CHO: Goodnight, ladies, goodnight ladies,
Goodnight ladies, we're gonna leave yer now!
So, merrily we roll along, roll along, roll along,
Merrily we roll along, on the good ship Shenandoah.

This is the way we roustabout ...

This is the way we tuck a splice ...

This is the way we stow a bunt ...

This is the way we heave away ...