is the shortened version of probably it can also be used in a notherway meaning "probibility" instead of probably (auctually I created this word, maby not first but it definetly came out of my head
independantly)
How Post Malone says "probably" in the song Better Now. Often said to look cool, or when was is overly drunk or high, and they are slurring their words.
Post: "You prolly think that you are better now, better now"