He mustn't drink. 
Three man went into a pub. They were all drunk and two of them were carring the third beetwen them. When they was inside they dropped him on the flor. Then they went in the bar. 
They said to the barman, two whiskies, please. 
The barman said, what about your frend ? Doesn't he wants an whisky? 
Oh, no, they said,he mustn't drink. He's diving.