OK, once my friends were going on an outing and me and my other friend couldnt go with them cos we had important stuff to do, so we thought we'd give them something to remember and called them on their mobiles when they were all in a group in hte car and pretended to be men who were stalking them, and we said we r watching u, and we r right behind u, and gave the location of where we thought they wd b on the road etc, their car description and singled out the driver for our special attention, threatened them all....
Later on the next day we asked how was your trip? They said something really bad happened and some guys were trailing them and they got freaked out, driver was so freaked out that he bashed the car with someone else and it got a bit damaged... Oops!
And that was one of the most innocent jokes i played.