Question on Using Dregs

There is no info on the WIKI about it but I gather that dregs are the leftovers from bottles whether homebrewed or commercial.

How would I go about utilizing these?
Do you let them sit for a day or 2 to let them grow something or would I use them right after I drink a beer?

I'm curious for the sake of making sour beers but I think I briefly read that you can harvest yeast this way. If there is already an informative thread out there that someone knows about please point me in the right direction.

I would encourage you to NOT use drugs, they'll rot your brain. Oh...wait...you meant dregs, like yeast?

Oldsock (a user here) has a fantastic funk-centric brewing blog that covers almost everything you would need to know. Here is the post regarding dregs, its a great read.

Harvesting Sour Beer Bottle Dregs | The Mad Fermentationist - Homebrewing Blog