A few years ago I pulled a nice April Fool's prank at my job.
I'm working in some sort of IT support, so I posted a message in the newsletter to the whole building that anyone could swing by on that day to receive a wireless mouse for free.
I was handing out mouse-shaped candy. Hey, they were wireless! ;)
@academicalnerd And everybody could appreciate it because it was a harmless prank and the pranked got some nice candy to nom on as consolation. :D