Search: grateful dead concert pyramids
Why: In the "Freaks and Geeks" episode Chokin' and Tokin':
FRANK: You into Floyd?Answer: Yes! On Sept. 14th, 15th, and 16th, 1978, they played at the open air Giza Sound and Light Theater at the foot of the Sphinx and the Great Pyramid. In October 2008, they released the shows in a 2 CD / 1 DVD set called Rocking the Cradle: Egypt 1978.
KEN: Oh! Hell yeah.
FRANK: I saw them at the Pyramids.
DANIEL: The Egyptian Pyramids?
KEN: Uh, I don't think they've ever played the Pyramids.
FRANK: Oh yeah. You're right. It was the Dead. I just got confused because I was thinking of another guy I went to both shows with. His name was Tim.

Source: The Rolling Stone
The More You Know: I've watched this entire show 3 times, but until now, I thought Seth Rogen's character was named Cam, not Ken. This is why I prefer my DVDs to have subtitles.