The one on the left regarded Xander carefully, and pursed his lips in thought. "Does that mean you don't want a custard cream?"
"A thousand times no," said Xander, before pausing in thought, "Although I might want to place a private order later. Do you deliver to America?"
"Hmmm…" said the one on the right, "Mail order – might be worth looking into at some point. Better ask Hermione how muggle mail works some time, Fred."
Xander looked back at the twin on the left, "So, you're Fred?"
"Actually, I'm George," he said and looked at his twin, "Fred's always doing that to new people."
"I thought I was George today," said the one on the right. "Even numbered day surely?"
"It is a leap year," said the red head on the left consideringly, "Tell you what… I'll be Fred then."
"No, no, you said I was Fred," the other said firmly, and turned to Xander again, "You sure you don't want a custard cream?"
Xander stared at both of them for a moment. "Okay, only one way round this. From now on, you're both Barney."