jaat buddhi
a person who thinks they're clever but can't even finish a sentence without making a mess of it
'You said you'd help me with my homework. You're a jaat buddhi!', @StudentStruggle
'She tried to explain her life story in three words. It was a jaat buddhi moment.', @LifeStoryFail
'He asked me a question, then answered it wrong. Total jaat buddhi.', @QandAFail