Bass Pro Shops brawlers got into a stink over a guy allegedly taking too long in the bathroom ... leading to the the s*** hitting the fan!

The rumble went down this past Saturday in Odessa, Texas ... and according to the police report -- obtained by TMZ -- the clash was caused by one guy accusing another guy of hogging the restroom.

The man told cops his wife and child were waiting to use the bathroom ... and when the guy finally came out, he told him he'd been taking too long and there were people waiting.

Cops say one of the men told them the tiff escalated ... with others getting involved, and the group eventually went outside -- but then came back into the store to throw down. X/@FactsAboutTexas

Fortunately, it looks like no one got wiped out -- but it did get messy ... with

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