The 3 craziest (read: worst) crowds I've ever seen were for the Saturday of MDF 2009, Megadeth in Norfolk, VA in 2010, and Motorhead in Stuttgart, Germany last November. Motorhead and Megadeth were just squishy and rough to the point of extreme distraction from the show, but it didn't completely ruin it. At MDF the crush was so intense during Bolt Thrower that I really couldn't enjoy the set it hurt so much. It was pretty much impossible to get out though. It sucked. At least it made since at MDF and at Motorhead to an extent given the size of the hall, it was just fucking stupid at Megadeth.
5/4 - Rob Zombie?
5/11 - Ghost
5/13 - Mastodon / Gojira
5/21 - Primus
6/28 - Iron Maiden / Ghost - Bergen, Norway