To thoroughly wash your hands for at least 20s to minimise the spread of covid-19.
Oi bruv, you'd better go kweff your hands, you don't wanna catch the 'vid!
To beat someone up, or attack them harshly.
Bro, if you saw the way that I kweffed that opp boy yute, man wouldn't be surprised if his broski left him.
Someone who sits on spotify all day
“Yo have you seen that dude kweff who just plays music all the time” “ye he has aura and motion tbf i bet he gets all the fine shyts”