I was fooled 3 times:
-by someone who told me that he had found my wallet empty on the street;
-by my deskmate who told me that I had took a 4/10 at the math testpaper (unbeliable I could say )
-by my mother who told me that she had seen a dog near our apartament door. I bet I was searching ''that imaginary dog" for over 2 minutes...lol

I was busy doing my thing around the interwebs, but my neighbor's entire family painted their skin entirely black and started running around the street yelling "zulu"

still not as weird as half the skyrim mods I downloaded that day.

I acted like i did something to my colleague's chair and waited for him to see me.
He was afraid to sit on that chair all day and kept asking me and my other colleagues if I did something to it.

http://forum.toribash.com/showthread.php?t=344858

Did I ruin it by posting?

Oh yeah, I told my ex-girlfriend I strangled cats to cope with the depression of dumping her.

=)))), that was very smart

Director of my school fooled us by trying to confirm that our Holidays was canceled....

Thanks. (Mersi fain).
That trick only works on April fools or if you are known for doing pranks.