I think he said "push push", like what a Music Man Big Al uses. Push it down and it stays down, push it down again and it pops up all by itself, push it again and it locks down. I have used those on guitars I've built, they are EXCELLENT for on-the-fly operation .... much easier to use that push-pull type knob/buttons. You can kinda just smack on it and the button will operate, you don't have to be so precise or bother with getting your pick oriented ok to deal with grabbing the knob to pull it up. Just bounce your finger/thumb/palm/knuckle/erverwhat on top of the knob and the button will either lock down or pop up all by itself. Wonderful little gadgets!
You can use a much wider selection of knobs with those as well, because they don't have to be something that you need to actually grab ahold of to pull them upwards, just smack 'em on the noggin' to operate the switch.