The man answers, "A scotch, please."
The barman hands him the drink, and says "That'll be five pounds eighty," to which the man replies, "What are you talking about? I don't owe you anything for this."
A lawyer, sitting nearby and overhearing the conversation, then says to the barman,
"You know, he's got you there. In the original offer, which constitutes a binding contract upon acceptance, there was no stipulation of remuneration."
The barman was not impressed, but says to the man, "Okay, you got a drink free this time,but don't ever let me catch you in here again."
However, the next day the same man walks into the bar.
The barman says, "What the heck are you doing in here? I can't believe you've got the audacity to come back!"
"What are you talking about?" replies the man " I've never been in this place in my life!"
The barman looks puzzled but apologises adding, " This is uncanny. You must have a double."
To which the man laughs and replies, "Thank you. Make it a scotch."