We love nothing more than a good prank but we have to say that if we had this one played on us, we'd be pretty terrified.
Basically, some evil genius decided to dress a dog up as a giant spider and scare the living daylights out of people.
Some of these reactions are brilliant.
https://www.youtube.com/watch?v=YoB8t0B4jx4#t=227
Video via YouTube/ SA Wardega. 
