It's impossible to force someone to sing.
It's even more impossible (yes, there are degrees of impossibility) to force Ben someone to sing the harmony in a song they really do not like.
"Tonight You Belong To Me" (277k wav) is a fun song that all couples should sing.
Life's too short to hold on to dignity*.
* I learned this lesson the hard way last week when, halfway through a business meeting, I realized that I had big chunk of chocolate stuck to the massive cowl-neck part of my turtleneck (the neck of the sweater can cover my entire head). Apparently, the piece of chocolate had fallen into the collar on the last occasion I had worn the sweater -- no doubt while laying on the couch, eating chocolate and watching Classic Hollywood Squares.


