When one goes into a hardware store for needed supplies, but realizes tools are needed to complete the job. Instead of purchasing tools, one opens needed tools and assembles product in store.
Guy1: We need to cut this pipe in half, but I too cheap to buy the cutter.
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.