The state between simply doing nothing and chilling out, typically reached whilst under the influence.
"Wheres Mike? I heard he was ripping tube all night."
"Oh, hes just over there in the corner on the beanbag, nillin."
"Hey man, what you been up to today?"
"Smoked a bowl earlier. Since then I've just been nillin in my room."
To not be doing anything. When one is nillin', he ain't doin' shit.
Man 1: So, what are you up to?
Man 2: Well, you know me. I'm just sittin' here nillin'
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