'Sure, that's what I mean,' Doc Daneeka said. 'A little grease is what makes this world go round. One hand washes the other. Know what I mean? You scratch my back, I'll scratch yours.'
Yossarian knew what he meant.
'That's not what I meant,' Doc Daneeka said, as Yossarian began scratching his back. 'I'm talking about co-operation. Favors. You do a favor for me, I'll do one for you. Get it?'
'Do one for me,' Yossarian requested.
'Not a chance,' Doc Daneeka answered.