Is this an expression?

I have a doubt, I don´t understand the meaning of wear collars in this sentence:
To make sure in a negotiation if someone wants something from you, they wear collars.
What thas it means?

This is a subculture expression that is not known in the mainstream.  If you want to know all about it, here's the link.

http://en.wikipedia.org/wiki/Collar_(BDSM)