S8E19: The Splendid Source
Bender heard it from Al Harrington,
Harrington from REO Speedwagon.
Heard it from a friend who Heard it from a friend who Heard it from another PETER: REO Speedwagon saved us several stops,
as they, too, had backtracked the joke to some extent.
But when their trail had led to a bartender in Virginia, they had given up,