When you are relaxing to the point that no person or reason can possibly compel you to relocate or do anything. Not to the point of a coma-like chill state, but more a presence of mind defying anyone to stop this chill session.
Laying by the pool with some drinks....chillin' tough.
In a recliner watching TV...chillin' tough.
The level of which one is just too chill, lit, and savage that others must refer to them as chillitavage so you don't waste their time blurting out the words.
Being in a total state of relax. Expresses the person is extremely chillin or in a maximum state of chill.
Can also be expressed as "Chillin in ma bones"
"Charlie smoked a couple doobskins and he is chillin in the bones"
"I hit that bong earlier and I'm chillin in the bones"