Crude and NSFW, but a must-see for any fan of Metalocalypse. This is the series finale, as they were never expected to be renewed for another season, so it wraps up all of the existing plots. It's hilarious and the most fun I've had with any musical.
The high point was the Toki and Skwisgaar guitar battle.
It also creates a new plot that begs continuation, but we all know how that worked out.