INGLEWOOD, CA - JANUARY 10: (Exclusive Coverage) Zakk Wylde, Dave Grohl, Lemmy Kilmister and Slash backstage during Dave Grohl's birthday bash at The Forum on January 10, 2015 in Inglewood, California. (Photo by Kevin Mazur/WireImage)
INGLEWOOD, CA - JANUARY 10: (Exclusive Coverage) Zakk Wylde, Dave Grohl, Lemmy Kilmister and Slash backstage during Dave Grohl's birthday bash at The Forum on January 10, 2015 in Inglewood, California. (Photo by Kevin Mazur/WireImage)