Insecure

Only the insecure people need to lie to make themselves appear smarter, more relaxed, less anxious/worried (or more so), and just better in general.

"I completely didn't read this chapter at all!" [Proceeds the ace the test, which DEFINITELY is not possible without reading the text]
"Oh, I'm not doing that, too much work." [Proceeds to do it, and claim that he/she had extra time]

I prefer to not talk to these people. Save myself AND them the trouble and annoyances.

I DO have a person in mind, although one of the examples didn't come from said person. Don't try to seem smarter or oh-so-chill all the time. I'm sick of you trying to put me down and make yourself feel better at my expense. If you want to think I hate you, go ahead. If it'll keep me from having to deal with you, then whatever. You can think I'm a b*tch if you want.