Here is a half-drabble - 50 words - not specifically a birthday fic, I'm afraid, this one is probably more aimed at Brits than Americans. BtVS, sometime in Season 5 or 6.
When the day is dawning
“It’s Wi-Wi-Wi-Willow,” Xander declared firmly.
“No, it’s W-W-W-Willow,” Spike insisted, equally firmly.
“You’re both wrong,” Anya told them. “It’s W-W-Wi-Wi-Willow.”
At that moment Tara entered the Magic Box.
“Ah, here’s someone who can settle the argument,” Spike said. “Glinda, help us out here. Is this the way to stammer ‘Willow’?”