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1.
Another term for sister. Usually used in a cute way.
A term of endearment.
I love her, you know? She's my little sissy-poo!

He is really mad at me because I dated his sissy-poo.

(singing) Happy birthday to you, my sweet sissy-poo!

Jenny can't come to the movies, she has to babysit her sissy-poo. (giggling)
by Juergen February 03, 2007
16 8
 
2.
a bitter, hateful, mean-spirited cruel ass bitch (that may or may not have had a sex change operation) that you are related to and HAVE to see on holidays and other family events. Can be used in the place of BITCH if bitch has been trivialized by over used at family events.
Is fucking sissypoo going to ruin Christmas again this year for the whole family. Who is the asshole that invited sissypoo to the family reunion. Did you see how rude sissypoo was to the waiter, I bet he spit on the bitches food when she sent it back. I got sissypoo'd when that bitch showed up for Thanksgiving.
by unfortunate sis February 12, 2010
9 3