Last night, Billy Joel, who’s playing Madison Square Garden once a month until he feels like stopping, had a pretty special guest come up and jam with him. AC/DC’s Brian Johnson joined Joel and his band for a rendition of “You Shook Me All Night Long.” As strange as that sounds (actually, it sounds like listening to a classic rock station for about 15 minutes), it’s not the first time the two have performed together. Back in 2002, Johnson and AC/DC bassist Cliff Williams did “Highway To Hell” with Joel, which Joel has performed since with his solo band. It’s not like Joel needs to prove himself as a hard rock musician. He did help invent the blast beat, after all.