The 39th president made the revelation in his new documentary, Jimmy Carter: Rock & Roll President  

Jimmy Carter, 95, would not reveal which of his three sons was involved in the brief moment

Chip Carter seemed to confirm that he was the son who enjoyed some pot with Nelson during a brief set break in 1980

'In the break I said, "Let's go upstairs." We just kept going up till we got to the roof, where we leaned against the flagpole at the top of the place and lit one up'