- As a slang term, this was used in a salutation-What's proper?-which basically was the equivalent to "how are you?". Because this inquiry is used almost everyday, it has been informalized in many novel ways over time-from "What's up?" to "What's good?". Proper in this sense seems to replace 'good', and this has allowed it to be used as a replacement for good in other instances.
Because something is "done proper" it seems that here proper is being used instead of the adverb properly. However, proper has more implications than the original definition of proper alone: appropriate. When something is said to be done proper, this is a subjective statement not based on any rules or regulations, but simply because the thing is impressive to the user.
Also spelled and pronounced as proppa.
proper
adjective; slang; zero derivation
used to describe something good or something that is done very well
Etymology : Proper originally was an adjective describing appropriateness or suitability, from L. proprius 'one's own, particular to itself'.
Source : "Kick game proper! No one can jock my swag!" (Translation: My shoe collection is so good, no one can copy my style) —friend through text message, November 30, 2008.
Last modified: 5 December 2008