1) A suit which represents "a major break through on the sowing machine".
The mirror ball suit is from the mighty boosh, from the episode the priest and the beast.
2) Mirror ball recently has been used as an insult by calling someone a mirror ball, or saying someone mite as well be one, as all they do it copy everyone else in many different ways.
You mirror ball, stop copying me!
This is the mirror ball (suit) :)