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1.
unbelievable, shocking, something that is hard to imagine though seems to happen on a potentially recurring basis.
Good grief, is he running around the neighborhood again in his boxer shorts?
by Doctor Livingstone May 19, 2005
 
2.
Charlie Brown's, Linus's, Lucy's, and maybe even Pig Pen's favorite exclamation to express frustration.
Good grief, Lucy! Why'd you have to pull the football away again?
by emiii April 10, 2006