Not every weapon has to look like much, as long as its bite is big, loud and deadly. When Agent J (Will Smith) takes the puny little Noisy Cricket from Agent K (Tommy Lee Jones), he is understandably upset. Only when he fires the pinkie-sized gun does he understand its power.
The weapon not only takes a chunk out of its target, but propels the shooter back dozens of feet. It is quite the weapon, but not necessarily put to its best use in Men in Black.