Probably Kain :laughing .. here's a little more info on it ... I have to admit, I think she'd have probably woken up at some stage while he was rigging it :
http://gawker.com/evil-boyfriend-scares-sleeping-girlfriend-with-deadly-706880138
edit: after rewatching that Carrie stunt, I think more of 'the public' were actors as well .... I've never seen a construction worker walk into a coffee shop also carrying half a scaffold pole .. you just wouldn't, would you? :laughing ....