B-hard - a person who thinks they're the best at everything but can't

a person who thinks they're the best at everything but can't even remember their own name without cussing

'He's B-hard. He cusses at the mirror when he can't remember his password.'

'I called him B-hard because he took credit for my idea and forgot his own name.'

'My brother is B-hard. He cusses at the fridge when it doesn't open fast enough.'