Led Zeppelin at the height of debauchery 1971.
Source: Reddit
Holy crap 1971 Led Zepplin - there was some hard-living going on during this period. This is back in the period when they would stay at the Riot Hyatt on the Sunset Strip - and rent out a full floor for maximum debauchery.
No other band has inspired so many myths as Led Zepplin. The most notorious story is said to have happened when they played the Seattle Pop Festival on July 27th, 1969. The group was staying at the Edgewater Inn. A groupie came back to the room. Somehow there was a mud shark involved - and the use of the mud shark to pleasure the woman.
If the story is true, there's now a granny out there in Seattle who has some amazing stories to tell.