Is "baddest" a proper word?

I just came across this documentary:

The World's Biggest & Baddest Bugs by Animal Planet

Is "baddest" a proper word? Shouldn't it be "worst"? What is going on here?

The OED shows baddeste and baddyst as Middle English forms and baddest as being in use from the sixteenth century onwards. It notes, however, that baddest is now non-standard and regional. For that reason it should be avoided in formal Standard English. Not all contexts, however, require formal Standard English and the package illustrated is clearly one that does not. It was no doubt chosen for alliterative effect.

It seems we are talking about two meanings of bad. The first meaning is well recognised:

bad: of unacceptable standard, unfavorable, inadequate, etc.

comparative: worse

superlative: worst

The second meaning is informal, and is not considered Standard English, but usage is fairly common:

bad: badass, not to be trifled with

comparative: badder

superlative: baddest

The documentary is clearly referring to the second meaning, so baddest is the correct usage here.

The word "baddest" does not describe the least desirable outcome. When talking about the least desirable outcome, the word you want to use is "worst". Many wouldn't accept "baddest" as a proper word at all.

"Baddest" is common slang though, especially when used in conjunction with "biggest". Its usage comes from using "Bad" as slang word to mean "Cool" or "Tough".