dash of happy" song, I'm going with the immortal Ray Charles. Hearing "What I'd Say" always puts a bounce in my step. Classic piano, and how can you not sing along with his call-and-response with his backup singers, The Raelettes?
The story behind this song, as I've heard it, is that he was playing a dance hall, the contract said he had to play 15 more minutes, and he was out of material. So he just started riffing on the piano, made up some words, the backup singers joined in, and they finished out the required 15 minutes.
In my house, the lyric "I'm gonna send you back to Arkansas" has been changed to "I'm gonna send you back to Oshawa." (Obligatory Canadian reference for the Sensual Goddess.)
I also note with approval that Ray Charles was a world-class horndog. He was quoted as saying that to be a Raelette, a girl not only had to pass the audition, she also had to "let Ray." When I need backup singers (The Maxettes?), the same conditions will apply.