We're English teachers.

I'm sitting in the back of a cab, thinking about English past tenses...

"What's another verb that ends in -ish? Wish... fish..."

"Dish."

"Wish, wished. Fish, fished. Dish, dished."

"Squish!"

"Squish, squished."

"I say squashed - 'I squashed a bug.'"

"But you can say squished, too."

"Yeah, but they're not interchangeable. Squashed is like..."
*smacking one palm down onto the other*
"...and squished is like..."
*slowly curling fingers into a ball as if squeezing playdough through them*

"So, I guess squished is more like a substance oozing out, and squashed is used for things you flatten."

"Yeah. So... the person in the middle of the back seat is squashed, but mud is squished."

"You can't squish just anything."

"Squash, squish, squish, squash."

"Can you squish a squash?"

"..."