I'd tell you about a girl that eats nothing but vegetables, but I'm sure you've herbivore.
The Black Cat With a White Spot
Aerith and Bob were talking.
"Say, Aerith", said Bob, "do you know if anybody in the village has a black cat with a white spot underneath its chin?"
"I don't think so, no", said Aerith.
They sat in silence for a bit, before Bob said, "Are you sure? Come on, think harder. Black cat, a big one, with a white spot underneath its chin."
"I'm pretty sure there isn't a cat like that in the village", said Aerith, getting visibly annoyed.
There was another minute of silence before Bob said, "But are you really, really..."
"YES!" Aerith yelled. "I'm really, really sure! There isn't a black cat with a white spot underneath its chin anywhere in this village! Nobody has one!"
"Well, crud", said Bob and gave a mighty sigh. "Then I must've run over the priest the other day."