But, Sugar tells TMZ Sports he's just as excited for his post-fight party -- 'cause he's debuting his own custom weeeeeeed after the scrap!!

O'Malley says his buddha-smokin' bros just whipped up Sugar Show OG -- a brand new hybrid strain -- in honor of his big night ... and there'll be plenty getting passed around Saturday night.

Can't say we're surprised -- this is the same kid who smoked up with Snoop hours after winning a UFC contract.

Sugar says he's been getting his fair share of hate since then 'cause the UFC's been giving him Conor McGregor-level hype ... but told us he ain't trippin' off it.

Think we know why ...