Sophomoric

/ˌsɒf.əˈmɔːr.ɪk/ adjective medium

Sophomoric behavior displays the overconfidence of someone who has learned just enough to think they know everything.

His sophomoric jokes about the professor's research revealed he hadn't actually read any of it.

Memory Trick

Think of a sophomore, a second-year student who often acts like they know it all despite still being inexperienced.