A lonjunction (lazy conjunction) of the two words "stupid" and "spectacular". It essentially means stupidly-spectacular. It can have either a positive or negative connotation depending on it's use.
"Sometimes he doesn't think about what he's doing and still manages to win in a stuptacular way."
"Letting Rich borrow my car was a stuptacular idea... he just crashed it into a tree."
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.