From the comedy God that is Barry Cryer:-
Hospital patient gets out of his bed, leaves the ward and hospital to cross the road to a pub opposite in his hospital gown and dragging his intravenous drip on a stand behind him.
As he enters the pub, all goes quiet as people part to allow him access to the bar.
Barman: What will you have?
Patient: A double whisky
Which he sips as he stands at the bar, while he chats to the barman
Patient: Of course, I shouldn't be having this
Barman: (concerned) Oh, why is that?
Patient: I've only got ten pence