Occurs when peeing late at night or early in the morning, (usually accompanied by an unfortunate boner) when the pee-er fails to turn on the light due to sleepiness - leading the pee-er to urinate in the darkness and get piss all over the floor.
Common responses include "fuck it" under the pee-ers' breath, but responses NEVER include cleaning the stray urine off the floor. (sometimes leaving the mother to clean it)
A trip to a grocery store, convenience store, or gas station for the sole purpose of buying an excessive amount of junk food and sugary drinks, usually with friends. A chud run often happens late at night and ends with everyone involved hating themselves afterwards.