come-uppance

More accurately described as a colloquial phrase, it means
"your deserved reward or just due" for an action taken or statement you have made. It always conveys that to be of a negative nature. It should be hyphenated as neither word, of it's own definition, conveys close to the meaning of the combination of the two; therefore the linkage of the hyphen is needed.

"Joe has always bragged that he was the team's best batter, but in the playoff game he went 0 for 4 and humiliated himself."
(Joe; therefore, got his just due or his come-uppance for his continual bragging and then, his abysmal failure.

naiive

Means extremely "naive", bordering on stupid. The additional "i" indicates the greater degree of naivete.

He was so naiive that he went to a Liars' Convention and came home believing everything he was told.