Here's the (in)famous performance of "My Generation" by The Who on the second season of The Smothers Brothers Comedy Hour in 1967. I believe the clip is from the film The Kids are Alright, and not the actual broadcast - but it's footage from the original show.
A few things you may or may not know about this performance:
The explosion (at 4:06) was considerably more powerful on the air than it had been in rehearsal due - reportedly - to drummer Keith Moon's encouragement of the pyrotechnics expert. It probably contributed to Pete Townshend's partial deafness and tinnitus, and reportedly caused Bette Davis (who was watching in the wings with fellow guest star Mickey Rooney) to faint.
The bit at the end where Townshend smashes Tommy Smothers' acoustic guitar was planned.