What is your most enjoyable tactic for scaring the guests?

I'm a big fan of the subtle scare that requires no screaming, words, or jumping out.

One of my favorites is sliding out from behind a wall already walking at the pace of the group and merging in behind someone and getting real close as they start talking and finally turn around and screammmmmmmmmmmmm.

Its usually funny because the people behind me are getting a great view of the scare and they are cracking up knowing what's going to happen to their friend when they realize its not one of them.

I also love the loyal husband / Boyfriend who sees me coming, doesn't say anything but steps out of the way so I can slide right up behind their girl.