Definition
Alternative form of wouldn't you know it.
How People Actually Use It
refers to the story told by Jim Cornette when a local wrestling promoter , faced with declining attendance , rigged a lottery to give a way a pony so his son won it , so we did not lose money on the deal . As a result anything is is obviously rigged is referred to as wouldn't you know who won the pony .
"Billy got picked to be hall monitor again . Well Wouldn't you know who won the pony"
Source: Urban Dictionary