After riding ones motorcycle, horse, or bicycle the body's natural defense mechanism kicks in resulting in constipation, and the inability to defecate.
"Man, after that race I really have to poop but I have terrible rider's block"

" I sat on the toilet for 45 minutes but couldn't push it out if I wanted to. I've got rider's block bad!"
by Rammin R Dixon October 29, 2014
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