They actually did this to my friend once. He didn't even have the seat belt thingy fastened and they didn't notice. He's crazy, though, so he didn't really freak out at all.
And I don't know if they count, but I love to leave my restraint as loose as I can on Diamondback, and a couple of times I have been in the processing of slipping during the first hill. Then the restraint always closes another few notches at the bottom of that hill and I'm safe... and sad... lol.