Here's what it could refer to:
* "Coffin" as a type of beer: This is unlikely. While there are some craft beers with unique names, "Coffin" wouldn't be a typical choice for a beer brand.
* "Bier" as a misspelling of "Beer": If this is the case, the question might be asking about a "coffin beer," which is a type of beer that is traditionally served at funerals.
If you're looking for information about a specific beer, please provide more details, such as the brewery or the location where you encountered the term.
Let me know if you have any other questions!