The Maid Minion is a Minion Rush costume. It currently costs $4,99 (US Dollars) or 1,200 tokens. Once equipped, the Maid Minion will find Freeze Rays quicker.
This is one of three costumes that increase the frequency that a particular power-up appears, the others being the Quarterback Minion, which increases the chances of getting a Mega Minion, and the Mariachi Minion, which increases the chances of getting a Banana Splitter. These abilities can be useful for completing particular missions in the Jelly Lab.
A maid costume was worn by Phil when he answered the door and was captured, apparently by Dr. Nefario.
Equipped with this costume, the first power-up will always be the Freeze Ray.