When used to describe a man, it suggests cunning and shrewdness in a negative sense.

Ha! Little do you know...

I shall try to do more of a metaphor--not exactly one of my strengths. Anu is as clever and as quick as a fox.
I was trying to avoid this usage as it is a plain old noun, but, since my judgement has been called into question...
Anu is a fox. And if anyone isn't clear on what that means, a la slang, I'll be happy to explain private.
(Bristles still aquiver.)