1. one who believes he or she is much more intelligent than he or she actually is, to an embarrassing degree
2. one who believes he or she is far more skilled at a video game than he or she actually is, to an embarrassing degree
1. Ever since Gabe got that finance degree he thinks he can solve the US debt crisis. He's such a foon.
2. Zach is always saying he's a 'champ 3 stuck in diamond 2,' but the foon hasn't hit a ceiling shot in his life.