Macneil - A Scottish family name that somehow became a word people use

A Scottish family name that somehow became a word people use to describe other things. Like, why is it also a type of bird poop?

My friend said my last name is Macneil. I asked why. He said, 'Because it's cool.'

I got a history test about Scottish names. I got it wrong because I thought Macneil was a type of pizza.

My dog’s name is Macneil. He’s not Scottish, but he’s got a cool name.