How do you guys deal with 'cuppers?'

if they reallllly feel like they must cup the mic to get those lows going then tell them to try doing the lows with their hand in front of their mouth. this simulates the cupping in a way but doesnt actually overpower the mic. having something in front of your mouth can create lower lows just because of the way the sound resonates in there more. im not sure how it works just try it. dont completely cover your mouth though.
 
Or just put a little distortion on the mic so when they hit it harder it sounds more aggressive. You could use a distressor or a pre amp that you can overdrive the input gain just a bit.
 
Sorry, this is a tad offtopic but does anyone know what kinda mic most AE's use for metal vocals. I remember watching the Lamb of God Sacrament DVD and Randy was holding something that looked like a LD condesor ... not sure what it was though.

I wanna invest in something to prevent the cuppage.