One song guaranteed to get an audience laughing is "Rufus and Beverly", by Mark Graham.

Rufus could play the piano
And he drove an American car
He worked nine to sundown in an office downtown
To save us from nuclear war
Beverly came from Seattle
Played the mouth harp quite well, so they say
She used to write songs in an old-timey style
In hopes she could sell them one day

Rufus and Bev became sweethearts
And nature would not be denied
They did the things lovers do under the covers
As happy as clams at high tide
Then one morning said Rufus to Beverly
As they lay in the fondest embrace
Dear I have to confess with some minor distress
There's an issue I fear we must face

For this body you see here before you
Was once more like yours than like mine
And I sought the compliance of medical science
To change to the sex masculine
Beverly stared back in amazement
Then said "Rufus, don't rue what you've done
For I have surrendered a masculine gender
For this other more feminine one"

So these lovers went back to their passions
And their passions were scarcely diffused
And the knot was soon tied, though deep down inside
They were ever so slightly confused.

Murray (currently writing a bawdy song called "I Can't Reset My Cookie, no Matter How I Try ....."