Here is the record of the formation of a brand new, accidental usage:
DrApathy1: I am + famished
Unsumupable: aww, you don't' have anything to eat in your room?
DrApathy1: just a bad of doritos
DrApathy1: and i def. don't feel like that
Unsumupable: haha... freudian, i think?
DrApathy1: peut etre
Unsumupable: just a bad of doritos... *sigh*
DrApathy1: what're you sighing about :-P
Unsumupable: i was trying to illustrate how sad your bag of doritos might make you
Unsumupable: :-( .. it's so BAD, this big bad bag of doritos i have. and it's ALL i have.
DrApathy1: what is up with you? lol
Unsumupable: it's just one big BAD of doritos
In an earlier post, Cristi wrote that with computers we articulate with our fingers. This sort of error "bad of doritos" couldn't be made accidentally speech-wise. Unless, perhaps a person was thinking to say "A Big Bad Bag of Doritios," and the words elided into one another. So maybe this could be a speech error too. Everyone skips over words and inserts words into sentences that are supposed to come later in the speech. The medium of communication determines the mistakes that are likely to be made. The switching of two letters is common in typing, while the switching of two phonemes is probably more common in speech. The "bad/bag" switch demonstrates both of these, but perhaps a mistake like "bad/back" would be more likely in speech than typing.
Whatever the reason for the original typo, it's interesting to note that "a big bad" is now a meaningful phrase, at least in a certain community. Since this conversation, we've begun to use the phrase to describe an overwhelming amount of a negative thing as in: "I've got a big bad of homework," or "well, this day is just a big bad." And the grammatical construction has taken on a life of it's own - now we can talk about "a big good" as well.