The one person, or 2 that alwyas is the bitch of the group and messes up all the time

v. collectively or individually finding someone/something to blame for a problem, as opposed to brainstorming which connotes finding solutions to a problem

n. the act of finding someone/something to blame for a problem

(from a TV ad for HD television)

That one person in your group who cant hang and breaks under pressure.

Anybody who drags you down, keeps you from thriving.