Chillin' like a villain

[Mark Zuckerberg]

Relaxing comfortably, stress free in an attitude of ready to party.
The Like a villain part of the phrase refers to how rich gangsters may choose to be enjoying some liquor, maybe some fine wine, smoking a blunt of kine bud (high quality marijuana), enjoying chill pills like blue valium or xanax and most likely listening to some music just enjoying the moment.
Its in the same urban family of just chillin which is kind of like
how a wine would chill...not frozen, just simply appreciating in value as time passes.