A single sycophant - One of these is like a smelly sock you can't throw away it's

One of these is like a smelly sock you can't throw away it's always there and it's always making you stink.

My brother is one of these and he still thinks he's the smartest even though he failed algebra.

My mom's coworker is one of these and she's always talking about her stupid kid.

My friend's best friend is one of these and he still thinks he's the best at everything.