A NON-SEQUITUR
Affable Old Gentleman (who has half a minute to spare). "I suppose now, my boy, you take a good sum of money during the day?"
Shoeblack. "Yessur, 'cause lots o' gintleman, when they wants to ketch a train, gives me sixpence!"
[Old gent finds the sixpence, but in thinking over it afterwards, couldn't see the connection.
THE TWOPENNY TUBE
"Hi, guv'nor, there ain't no station named on this ticket!"