Im sure it's supposed to be short for, 'I cant be bothered to figure it out, you do it!'
here is the explanation....Go figure....This expands to "Go and figure it out", and means: "The reasons
for the fact just stated are unknown and possibly unknowable. You
can waste your time thinking about what they might be, if you
choose, but you're not likely to accomplish anything." (Kivi
Shapiro)