keep coffin like that and you'll blow a casket.

A Halloween Q&A from Grammar Girl:

In honor of Halloween, I thought I'd answer this question from Stephen P: "I would love for you to do a show or newsletter on 'casket' and 'coffin.' Are they interchangeable? What are their origins? I just read a book (Two For the Dough by J. Evanovich) in which these two words were used often. It made me wonder."

Coffins and caskets are both boxes in which people are buried. What differs is the shape. A coffin is wider in the middle and narrower at the ends. It's the shape you often see of the boxes standing on end where vampires sleep in old movies or of the lawn decorations you can buy for Halloween. Caskets are rectangular and are usually larger and more expensive than coffins.

Some sources say that coffins are more common in Europe and caskets are more common in the United States; other sources say that "casket" is a euphemism for "coffin" and that the term is only used in the United States.

The word "casket" originally referred to a box for jewels and may come from the Old French word "casse," which meant "box," and which took an "-tte" ending ("cassette") to mean "little box."

The word "coffin" is thought to originate from the Greek word "kóphinos," which was a kind of basket.