As part of the promotional push for the new film Grown Ups, David Spade and Chris Rock visited Howard Stern's satellite radio program. That's fairly predictable, right? As is the probability that Stern would get Spade and Rock to dish on who's got beefs with whom. This audio clip opens with a clip of Rock giving it to David Letterman earlier this year. But skip ahead to the 2:50 mark and you hear Rock explaining how he works on new stand-up material, and describes his surprise visit to the Sunday night showcase Hannibal Buress runs in Brooklyn at the Knitting Factory in Williamsburg. Rock talks about how he tests his new stuff in front of all sorts of crowds, including one full of "hip" and young people and comedians. Rock also says that he won't put any new tour dates on sale until he has spent at least six months or more making sure the new material is worth the ticket price. Well, why am I telling you what he said when you can listen to it, right now: