Supercross rider Cameron McAdoo let it all hang out during a race over the weekend ... suffering a truly unfortunate wardrobe malfunction in the crotch of his pants -- forcing him to complete the event with his junk on full display!!
The NSFW moment went down at the start of the 250SX East event in Detroit ... when McAdoo took a handlebar to the twig and berries after getting caught in a pileup at the beginning of the race.
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The mishap ripped his trousers wide open .