Quebec, Canada, slang for French-Canadian. Based on Pepsi's early marketing as a cheap substitute for Coke. Early jingle: "Pepsi-Cola hits the spot/Twelve full ounces, that's a lot (Coke had 7 ounces)/Twice as much for a nickel, too/Pepsi-Cola is the drink for you". The slur was that French-Canadians were also cheap imitations.
"These two Pepsis go into a bar..."