He lost the argument, but he still called me a 'moron' for winning. That's not a good loser, that's a sore loser with a mouth.

She lost the bet, but she still said she'd win next time. That’s not a good loser, that's a delusional fool.

He lost the game, but he still said he'd win again. That's not a good loser, that's a stubborn idiot.