Giving oral pleasure after the receipt of an unexpected gift.
Hillary received a beautiful engagement ring. Right after, she was caught on camera duffing her boyfriend on the barcalounger.
The act of living with the bare minimum required to maintain the ultimate bachelor lifestyle.
Those "duffing it", often live in an environment that only a true single man could tolerate. Normal living spaces may be converted for storage of motorcycles, beds may not have ever worn sheets, dishes may be piled up waiting for execution via the trash can.
Oh man Bobby is duffing it, he has a guitar stand where his dining table should go.