(her letter)

"M" is for the many times you made me
"O" is for the other times you tried
"T" is for those tawdry frat house weekends
"H" is for the Hell that's in your eye
"E" is for your everlasting passion
"R" is for the ruin you've made of me
Put them all together, they spell M-O-T-H-E-R
And that is what I think I'm going to be.

(the response)

"F" is for your funny correspondence
"A" is for this answer to your note
"T" is for your tearful salutation
"H" is for your hope I'll be the goat
"E" is for the ease with which I made you
"R" is for the rube you think I'll be
Put them all together, they spell F-A-T-H-E-R
But you'll never pin that title, dear, on me.

Thanks to Oscar Brand, "Bawdy Songs Goes to College"