Terri,

Everyone else is showing off on your dime (and not always very impressively) but I am going to resist the temptation to write a verse, and instead give you some serious advice about writing comedy--

First--remember that they key element to comedy is surprise(or shock)--and the most common way to do that is with contrast

Note the contrasts in Amos' contribution:

His friends gather round him
Both loyal and true
And haul him by elbows
And feet to the loo

The initial image of friends loyal and true is shattered by the hauling to to loo--

and so it goes--you take them in one direction, and suddenly go somewhere else--

The surprise of your premise will get you a laugh--but then you've got to come up with another surprise that is just as good or your song stops being funny--And there is a "three on a match" idea about the subject--Introduce a subject, like" log roll", make a follow up joke, then move on--

Timing is another element--you have to create enough "air" around a punch line so that people can understand it and digest it, but at the same time, you have to keep em coming--

The "Bob Hope" formula is to have a joke every ten seconds, which, in this song, means at the end of every couplet-- They don't all have to be equally funny, but there should be a couple of real zingers during the song, and one that has the same impact as the initial gag at the end--

As you can see, most important thing is the pacing--a funny premise gives you one laugh, then you've got to keep the audience's attention for about three more minutes--

Don't worry to much though--funny songs are more entertaining than jokes, because even when it isn't funny, it's still a song!!