An Auto-Antonym, can mean to do something with great vigour or with little enthusiasm. Context specific.
1. To attack something with vigour. Evolved from the noun Biff meaning a sudden sharp blow or punch
2. To have sex very enthusiastically. Linked noun Biff.
3. To stroll about meaninglessly. Origin unknown.
1. Brigadier Ben Ritchie Hook in Evelyn Waugh's Sword of Honour Trilogy: "Time for a Spot of Biffing!" (In reference to attacking the Enemy during the Second World War, immediately before he storms a pill box, alone, armed only with a machine gun and grenades)
D: "I heard you biffing last night O, keep it down next time"
O: "Sorry D, I had no idea I was so loud."
D: "Its alright man. It was pretty funny actually, you sounded like a cavalry charge"
D: "How was your day?"
O: "It was okay I guess. I biffed around town for a bit, but it was pretty pointless"