An Englishman says to his friend, the Scotsman, that he has a perfect way of eating for free in restaurants. 
"I go in at well past 9 o’clock in the evening, eat several courses slowly, linger over coffee, port and a cigar.  
Come 2 a.m., as they are clearing everything away, I just keep sitting  there until eventually a waiter comes up and asks me to pay. 
Then I  say: 'I've already paid your colleague who has left.'" 
The Scotsman is impressed, and says: "Let's try it together this  evening." 
So the Scotsman books them into a restaurant and come 2 o’clock they are both still quietly sitting there after a very
full  meal. Sure enough, a waiter comes over and asks them to pay. 
The Englishman just says:  "I've already paid your colleague who has left." 
And the Scotsman adds:  "And we are still waiting for the change!"