Wearing lucha libre masks and animal costumes, the Lollapalooza crowd came ready for oddball favorites Tenacious D. The duo, comprised of funny actor-musicians Jack Black and Kyle Gass, provided the comedic relief on a steamy Saturday with a slapstick symphony that covered the gamut of all four of their releases up through “Post-Apocalypto,” released last year.

The beauty of Tenacious D is that they don’t ever take themselves seriously, but they’re really good at what they do. The set is quite rehearsed with fake fights (Gass “quit” at one point in the show and a stagehand cried at the song “Roadie” dedicated to him), along with humorous one-liners and more phallic imagery than in a teenage boy’s bedroom.

Yet the duo are actually good songwriters and Black’s vocals are always top-notch, not to mention his mastery of the Sax-a-Boom kids’ toy (the solo may be one of the highlights of the weekend).

Songs like “Kickapoo” and “Tribute” were instant sing-alongs lying at the intersection of “Spinal Tap” and Simon & Garfunkel, a weirdo “Spamalot” rock opera that, once you’ve seen, you can’t forget.