fatty and thinny
[examples] Two subjects of a perpetually expanding song. The pattern of comedy would follow the Little and Large model, wherein Fatty would fart or do something amusing, and Thinny would either suffer, or not be involved. Thinny never got the laughs, and probably fantasised about Fatty's death in many different ways - if my understanding of murder motives is correct.
written by Jo* B*yth, Jo*De*ha*, approved by Log

A freindly version;
Fatty and Thinny were in the bath,
Fatty blew off and Thinny laughed.
And a recent ad lib by a friend;
Fatty and Thinny were in the hay,
Fatty blew off and Thinny was gay.
written by Ha*ry N*ce, approved by Log

Fatty and Thinny went to the loo,
Fatty did wee wee and Thinny did poo.
written by Ro* Jo*nso*, approved by Phil

Fatty and Thinny went to the zoo,
Fatty liked monkeys and skinny did too.
written by Ro* J*hns*n, approved by Susan

Also refered to as Fatty & Skinny. This didn't really effect the meter or maturity of the rhymes, as this couplet demonstrates.
Fatty & Skinny went up in a rocket,
Fatty came down with shit in his pocket.
written by Ma*ky*Mar*, approved by Log

And for the children whose brainpower was in constant battle with tartrazine-fuelled hyperactivity...
Fatty and thinny went on a hunt,
Fatty's a fat cunt and thinny's a fucking twat.
written by Ro* Mar*h, approved by Log

Fatty and Thinny went up in a rocket
Fatyy came down with shit in his pocket
written by Ro* V, left hanging by Edward

Fatty and skinny went up in a balloon
Fatty farted and skinny fell down

Shut up, fucktards, it works if you went to school in Newcastle.

written by sa*ah*dobs*n, left hanging by Edward

We had a slightly different variant:

Fatty and Thinny went up in a balloon,
Fatty let a fart off and blew Thinny down.

written by jo* omen, left hanging by Edward

Fatty and Skinny went on holiday
There was a fucking storm and it blew the cunts away
The kids all laughed and pointed as Skinny blew around
But Fatty crushed the bastards when he fell back to the ground.
(Optional "a-men" at the end.)
written by excluded pupil, left hanging by Edward

The version I remember ran thusly, in this way as described:

Fatty and Skinny went to bed,
Fatty rolled over and Skinny was dead.
written by Ol*ve* L*vy, left hanging by Edward

Fatty and Skinny went to the shop Fatty let off and Skinny went "pop!" Fatty and Skinny went to the zoo Fatty let off and Skinny went "Pooh!"
written by An*eMa*ie*Patt*nden, left hanging by Log

Fatty and Thinny were in the sea,
Fatty did a fart and Thinny did a wee.
written by an*nymo*s us*r, left hanging by Log