As far as I'm aware, it's just the slang I've heard growers use for useless plant material when you're going specifically for seeds. 

Probably the most efficient way to harvest all of your seeds is to dry out your buds to an extreme point and then you just grind up that plant material and get the seeds out of it.  

 Wait what…Really? 

 That's the way every grower I've known has done it. ¯\_(ツ)_/¯  

 Is it just considered waste material? 

 No, you can make it into butter/oil, or tincture. Also it still smokes like the high mids we used to get in high school.  

 Awesome 

 Never infused lard before, so that's my plan this winter when I can render!  

 Nice… I’ve never infused anything before. 

 Really easy with butter!  

 Mom use to make brownies. 

 We infused whipped cream for pumpkin pie one Thanksgiving. Funniest game if cards against humanity.  

 When I got in trouble as a kid Mom would give me "timeout" and hand me the stash box so I could strip seeds out and roll joints. 

Piss me off and I'd "accidentally" leave a seed in the middle of a joint.