Yikes. Do they pat you down or what? Or do they just ask you and hope you don't lie? (Sorry I'm asking so many stupid questions... I have yet to go to a park with such a draconian policy)
In addition to about 3 or 4 large signs, the person at the front is watching pretty closely and asking everyone if they have a phone. You're allowed keys, wallet, etc. in secured pockets, just not a phone. If you wear glasses without a strap, they'll even tell you to put them in your pocket. The ride operators MUST pull down your lapbar, and they don't allow any riders to do it themselves. If anyone does, they unlock that row and reset until the ride op pulls it down. I'm guessing that's also a way of looking for any sort of phone shaped object in people's pockets that may have slipped through.
Ops pushing down the lap bar is a fairly new policy as well, I was there in July and I don't recall them doing that and I was there this past Sunday and they are very strictly enforcing the lap bar policy.
I spent Memorial Day and the Tuesday after at KD, and they were enforcing the op pushing the lapbar down rule the whole time I was there.