When a stat has reached level 99 (e.g. maxed Strength); when someone hits their max hit on a person (maxing); when someone has a combat level of 138 – often referred to as "maxed cb" or "max melee"; or when a player has reached the maximum experience (30,000) through the Assist System and cannot assist for a few hours.
Usually means the buying of very large amounts of an item on the Grand Exchange to cause the price to unnaturally go up, then selling that same item later on in order to make a profit. It is also a term referencing free trade, when a player could buy an item at one price and then flip it for a profit without restriction.
May also refer to other profit-making activities using the Grand Exchange and/or NPC stores such as 'flipping', however these alternate uses are less common.