The shopkeeper has just asked you if you are an American. He cannot tell the difference between
Canadian and American accents. Americans are not popular in Britain. Their pay is very high
compared to British soldiers, sailors or workers so they get a lot of attention from the local girls.
Americans sometimes aren't very appreciative of British ways and how much the British people have
already sacrificed for the war effort.
Once the shop keeper realizes you are a Canadian - or a "colonial"- he's delighted to help you. You
get great service and the shopkeeper invites you and your pals to come "home to tea" - an invitation
to dinner. After a home cooked meal you thank the family and head out to the local pub.