A person who only shows up to an event or occasion every so often and not all the time.

Its name derives from people who only go to church on Sunday and not on other days on the church calendar.
Guy 1 - Where's John? We haven't hung out with him in ages.
Guy 2 - He's just a Sunday Boy, forget about him.
by JohnSmithLad August 5, 2011
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Go and appreciate all your chubby boys❤️We love them big, and chunky🙇🏻 ♀️
Joe: Fuck John why is he so fat
???:Dude you can’t say that, do you know what day it is!?
Joe: What day is it?
???: It’s chubby boy Sunday

Joe: Damn my bad John we love you❤️
by ChubbyBoyLover December 5, 2021
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When a man is in such a state after a night'ont town. That he can only be a Sunday boy
Hey mate, your a real Sunday's boy
by Sunday's Friday June 5, 2015
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