Twinking
Twinking describes a low-level character receiving high-level equipment, usually from a high-level character, which the low-level character wouldn't normally be strong enough to acquire on their own. This places them at an advantage compared to other characters around their level whose equipment tends to match their level. Twinking is similar to piggybacking, where a low-level character sits in the background while much higher level character defeat monsters well beyond their class so they can get experience much faster.
Twinking typically appears in role-playing video games or games which require frequent equipment upgrades like looter shooters. When playing on a team, or when a single player has a party, twinking is often encouraged, and players are often grateful to receive the equipment upgrades. However, in massive multiplayer games, twinking is more likely to be frowned upon by players who don't have experienced friends giving them gifts. In fact, the term is often used derogatorily and is based off the slang term "twink" which refers to a smaller effeminate gay man with a larger boyfriend.
Online video game companies also aren't fond of twinking because they make their money from subscriptions, and, anything that causes characters to reach their level caps faster ultimately cuts into their profits.
Twinking, is rendered far less effective in games which institute level requirements for equipment since a character can only use equipment which is around their relative level. Because of this, I assume that level requirements were created specifically to prevent twinking, since they aren't really necessary in games where players don't have the ability to share items. However, I don't know of any evidence to prove this.
Personal
In the mid-1990s, I was playing Legend of the Red Dragon which allows the player to instigate PvP against other characters. I went after a level 1 character assuming I would get easy victory, but when I encountered him, the game told me he was wielding the most powerful weapon in the game! I assumed it must be a trick or a bug in the game, and fought with him anyway, but was killed in a single hit. On the game's message board, I accused him of cheating, and he explained that he had another very powerful character which he used to buy the weapon, and then simply gave it to his other level 1 character so he could level that character up much faster. This was the first time I ever learned about, what would later be called, "twinking." Initially, because it negatively affected me, I viewed it as cheating, but, after thinking about the utility of it, I began using the same trick myself.