Q: What's that song you see on tv bar mitzvah songs it gos da da da, da da da da.
A: I don't know what to make of the "da das", but the most common dance song for Bar/Bat Mitzvahs and Jewish weddings is Hava Nagila. Here's a bizarre clip of a Beetles tribute band doing their version of it: http://www.youtube.com/watch?v=vTmt6ZD-G_c&feature=related