What does the word “doofosity” mean?

I have already tried to look up doofosity in many dictionaries but met with no success, so I’m asking here: what is the meaning of doofosity?

Solution 1:

Doofus, also dufus is an AnE slang term from the '60s which is both a noun and a modifier:

(modifier)

• Many another dufus play among friends

(noun)

• A fool; idiot; airhead, birdbrain, boob: He'll do his best to make you feel like a doofus/ But this is the doofus you have to deal with, so hush up/ I have to be in front of this self-important doofis with his portable phone/ I felt like such a dufus/ when some big, loud, popcorn-chuggin' doof and his date sit in front of me.

Origin:

• [1960s+; probably related to doo-doo and goofus]

Doofusity is the quite rare abstract noun from doufus that refer to the quality of being a doofus.