Usage patterns
大の怠け者a real lazybones; a total slacker
He's a total slacker who sleeps all day on his days off.
〈人〉を怠け者と呼ぶto call someone a lazybones
If you don't do your homework, everyone will call you a lazybones.
怠け者のくせにeven though (someone's) a lazy person (used critically)
Even though he's such a lazybones, his grades are surprisingly good.