Mostly used in the debating community. Overwanking means that you’re hyping up a fictional character by saying they are significantly stronger and more powerful than they actually are without much to back it up.
Example Overwanker - Naruto & Sasuke can blow up Planets.
Normal Person - No they can’t, thats overwanking them.
Similar to overclocking a PC, but in human terms. Ultimately, it leads to failure of the component, usually causing it to over state its worth and sleep late. It typically only sounds like a good thing to the one practicing it.