The Maid

The Maid is a weapon which Finn and Jake used to try and kill The Lich in the episode "Crossover." It represents itself as a helper (assistant) as hinted by it's name "The Maid," and when being fired, a female voice saying "Housekeeping" can be heard.

The Maid is aimed to be used to take out inter-dimensional beings that pose as a threat.

Appearance
The Maid is a pink in color cone shaped weapon. The color lightens closer to the pointed edge (The muzzle of the weapon.) The flat side of The Maid contains instructions written on in cursive.

Instructions
The Maid

"The Maid will handle all Class A interdimensional Bung-ups if you follow these simple steps:

Direct the small end of the maid toward your massive mistake.

Focus your intention until all distractions leave your thought sphere.

Then recite the words "A man needs a maid" three times.

P.S. don't mess around and point the maid at your buddy, you goof.

You already screwed up once.

Trivia

 * Based on the last paragraph of the maid's instructions, it is clear that the maid has been used more than once.