In yet another photo borrowed form Ernie's photo album, we see (from left to right) Cookie Monster, Ernie, Elmo, Bert, and Grover who were (except for Bert) all on a very bad Acid trip, hence all the weapons. It is said that a Security Guard working that night took the picture but he went missing the very next morning and the word down on the "Street" is Bert took care of him so no one would find out of his their little adventure.

Thanks to,
J-roen
for getting & sending us the picture