a secret plan or scheme to accomplish some purpose, especially a hostile, unlawful, or evil purpose:

when you're hungover as shit after a spending a night drunk as a skunk

Hanging out/ cotching. Having a little jam with a couple of people.

Can be abbreviated to plottin

The creation of a horrible plan. People who plot will always refuse to tell any of their plans to their friends. People who plot will often come in pairs, wanting to plot together against their friends and/or partners.

Definitely different than scheming, you'll know it when you see it, just know it definitely looks different than scheming.

(v) When a large group of young people all park their cars in an abandoned parking lot, tune into the same radio station, and proceed to have a dance party. From the word "plot", short for "parking lot"

When you are too lazy or don't want to watch a movie for any reason, but you want to know what happens and why everyone is talking about it. So you decide to go on Wikipedia and read the movie's Plot.

This can also be applied to books, TV series, etc.