There were a number of them.
Unfortunately, the only one I can remember at the moment is this one:
"Ohhhh.. I wonder, wonder wonder wonder who... who wrote the book of loo-oove..."
(Thanks to Sarge!)
Or he'd have some wry non-sequitur like,
"Here's some music to type by." (?)
And then put on CCR, "Bad Moon A'Risin'"
And any time the song "Tequila" was on, he would not fail to say:
"They don't write 'em like they used to. Thank goodness."
Also funny when he'd purposely set you up (and you were like his 10-year-old kid) by asking you a question, and he'd be like, "No. It's..."
(and the "answer" was a song lyric; often a totally inaccurate statement.)

This call anything to mind for anyone else?