Research

http://www.youtube.com/watch?v=niBsIMdy01c
I'm pretty sure this isn't real

http://www.youtube.com/watch?v=s9LXPmrbQ1o 
some simple 'scarings'

http://www.youtube.com/watch?v=PqWmT1HUjFY
easily scared man

http://www.youtube.com/watch?v=jfBBW34a2wY
scaring the wrong person

http://www.youtube.com/watch?v=X_2_83nnLWo
japanese scary prank

http://www.youtube.com/watch?v=5XRjcKiAyto
nice defences

http://www.youtube.com/watch?v=kIXiJotHSSQ
scaring from a box

http://www.youtube.com/watch?v=kI07KRxhnBM
ellen scaring people

http://www.youtube.com/watch?v=h6qE7bxunyo
anticlimactic wrong scaring

http://www.youtube.com/watch?v=lnDa2Zqvl6c
more quick reflexes

http://www.youtube.com/watch?v=S44Suzi60cE
they always miss the actual scaree because theyre laughing

http://globalgrind.com/2013/09/09/prank-gone-wrong-man-shoots-teen-jumping-out-of-closet-photos/
http://www.nydailynews.com/news/national/track-star-shot-killed-prank-wrong-father-article-1.1449117
gone terribly wrong (if true)

http://www.youtube.com/watch?v=slUC2KMyj2Q
compilation