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1.
An expression used to fill a pregnant pause when someone simply says "so" either as a way to start a conversation (but is not sure what to say) or as a reply to something they are not impressed with.

Also can be referred to as "Sew buttons on your underwear."
Example #1

Girl #1: So...?
Girl #2: Sew buttons.

Example #2

Girl: I just had a 5 minute conversation with Stephen Fry at the mall!
Boy: So?
Girl: Sew buttons.
by goellegee January 03, 2014