Here's one of dozens of versions of this:

Crab Song (Collected by MacEdward Leach)

Good morning, Mr. Devil, morning, sir, he said,
Whack fol the didlle-o the diddle-i-day;
You've got a crab which you'll sell unto me,
To me all whack fol-de-diddle-i-dee.

I got a crab fish one, two, three,
Whack fol the didlle-o the diddle-i-day;
And the fattest of the three I will sell unto thee,
To thee all whack fol-de-diddle-i-dee.

Jack took the fattest by the backbone,
Whack fol the didlle-o the diddle-i-day;
Like a damn fool came swigging on the rum,
To me all whack fol-de-diddle-i-dee.

And when he got home for the want of a dish,
Whack fol the didlle-o the diddle-i-day;
Put him in the pot where the woman had to piss,
To me all whack fol-de-diddle-i-dee.

The woman got up and she did want,
Whack fol the didlle-o the diddle-i-day;
Crab fish caught on by the you-know-what,
To me all whack fol-de-diddle-i-dee.

Old man, old man, now do you come hither,
Whack fol the didlle-o the diddle-i-day;
Devil's in the pisspot tearing up your lover,
To me all whack fol-de-diddle-i-dee.

The man came peeping, as I suppose,
Whack fol the didlle-o the diddle-i-day;
Crab with his other claw caught him by the nose,
To me all whack fol-de-diddle-i-dee.

Run, boys, run get the looking glass,
Whack fol the didlle-o the diddle-i-day;
See your daddy's nose stuck up mommy's ass,
To me all whack fol-de-diddle-i-dee.

One got the poker, other got the stick,
Whack fol the didlle-o the diddle-i-day;
More they beat the crab fish, tighter held his grip,
To me all whack fol-de-diddle-i-dee.