Comedy challenges taste and convention and it can rouse strong reactions as we saw at this year’s Oscars when a joke earned comedian Chris Rock a slap in the face from the actor Will Smith. Stephen Sackur speaks to the comedian Omid Djalili who has spent more than 25 years finding laughs in sometimes unlikely places. He was born in London to Iranian parents and has thrived as a cross-culture comedic chameleon. But is it possible to be funny without being mean?