A name used to describe a home girl that has sex and/or performs sexual favors within her group and neighboring groups..usually turned out by alpha members of groups..." Ratchets are easy to turn" and like a hood-rat everyone can get a turn. But not just anyone.

The Medical Officer from Transformers, not a disgusting human being.

a tool used for assembling and maintenance on an automobile, not at term used to describe a slut

A term that Ignorant people use to describe others.
People of this sort are calling each other a type of wrench, that moves in a ratcheting motion, It is not a name to call someone, it is a tool often used to work on things with nuts and bolts!

A type of lockback folding knife originally from Germany. These are very popular in much of the Africa and much of the Caribbean. Ratchet Knives are often associated with gangs and criminal activity. In Jamaica they were closely linked with "Rude Boy" street culture.
Ratchet Knives are named for the ratcheted blade lock mechanism.

The ratcheted blade lock mechanism keeps the blade from snapping shut on the user's hand even when only partially opened. The ratchet knife is usually unlocked by using a pull ring on the back rather than the more common push buttons or levers of most lock blades.
Both of these features make it less likely for the knife to snap shut across the user's fingers during a struggle.

However the key to the popularity of these knives is mostly due to their extremely low price, wide availability and intimidating ratchet sound on opening.
The most famous brand of ratchet knife is the Okapi. Originally made in Germany for export to German territories in Africa the production of Okapi knives moved to South Africa during the 1980's where it is still a very popular all around knife, especially with local criminals.
The Okapi was also the favored ratchet of Jamaican rude boys who often referred to them as "Three Star Ratchets" due to the three stars inlaid on the handles of many Okapi brand ratchet knives.

when a person goes crazy or they dont care what they do

A mispronunciation of "Rat-Shit". Typically used by Australia youth as a localised version of the American equivalent, which refers to ghetto-trash and ghetto-trash-want-to-be persons of the female variety.