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.
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"