He is a 'madman' out on the ski slopes. [=he is an extremely daring or reckless skier]
He drives 'like a madman'. [=he drives very recklessly]
a celebrity being stalked by a 'madman'
(..) Maybe l did. l wss packing up our bsse camp... at the Cave of Swimmers. Clifton had offered to fly down from Cairo to collect me. He flew like a madman always so l... l took no notice. Asah! Katharine? Dear God, Katharine what are you doing here? (..)1996 The English Patient