I threaten to "duff up" my warehouse manager up occasionally....
(he is 6ft 6 and an ex boxer, no way I can even scrape his chin)
"Duff" had a couple of meanings
This bit of Scalextric track is duff -- it is broke.
Duffed up - got beaten up by kids at school again.
My girlfriend is up the duff (pregnant) -- My girlfriends dad is coming round to duff me up.