The phrase used to describe running whilst needing to excrete one's bowls, the sufferer then has 2 choices:
- clench their arse and hope for the best
- shit their pants
"Paula Radcliffe shit herself in the marathon", "oh yeah we've all had runner's bum"
by Mahoganay October 12, 2013
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When you need to shit whilst running and you must clench your asscheeks to hold it in.
- "Hahaha Paula Radcliffe shat herself mid race", "ah, we've all had runners bum"
by Mahoganay October 28, 2013
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A drink made by someone homeless, or soon to be homeless, combining at least 10+ different drinks that have been removed from a garbage can in a party district.

Also known amongst the homeless community as a "Sidewalk Sleeper", this is semi-common activity in Bourbon Street, New Orleans, LA.
The homeless guy made a Bum Runner on Bourbon Street as tourists laughed and photographed him in the act.
by Brandon "Batman" Green June 15, 2011
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