U S A, U S A
How offensive. Everyone knows the possessive 's' requires an apostrophe!
Really, at this point just go the extra inch and add the 's.
Just going to the office. TO FIRE THIS GIANT GUN! Hah, the military is SWEETNESS.
"Really bored while driving from S. Carolina to CT in the rain."
"My friend sent me this pic from Seoul, S korea. I wish i knew what the buttons were for."