I don't really get the point of kissing someone with a song, It's just nonsense, but if I have to do, i will choose my big ol' collection of 1960 bands, like Beatles.
I'm tempted to say pictures or this didn't happen... But I might just settle with the opening theme song, seeing as ponies brought you together(?) and it's the beginning of a relationship - It makes sense to start with the first song of the show !