piece of ass

NOUN
12 LETTERS · STARTS WITH P

piece of ass is a valid 12-letter word worth 17 points in Scrabble and 19 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
P3I1E1C3E1O1F4A1S1S1
3 + 1 + 1 + 3 + 1 + 0 + 1 + 4 + 0 + 1 + 1 + 1 =17 PTS
DOUBLE WORD → 34TRIPLE WORD → 51
MEANING

What does piece of ass mean?