A security guard. Derived from 5-0, slang term for a cop. Security guards carry about half the credibility and authority as a regular cop, hence the 2.5.
See also rent-a-cop, mall security.
"Bobby and I were throwingmustard off of the balcony, then some 2.5-0 come by and threatens to calls the cops. Lame"
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.