Mine: Merry Christmas from the Family. Every single time I hear it, I laugh. But really? It's terrible.

Some great lyrics:
"Brother Ken brought his kids with him
The three from his first wife Lynn
And the two identical twins from his second wife Mary Nell
Of course he brought his new wife Kay
Who talks all about AA
Chain smoking while the stereo plays Noel, Noel"

"Send somebody to the Quickpak Store
We need some ice and an extension cord
A can of bean dip and some Diet Rites
A box of tampons, some Marlboro Lights"

What's yours?