This is a prank i used to do to people at college and once to myself (It is that good) where a music file is hidden in the start-up folder which would normally be annoying or irritating.
Hope you find this instructive and helpful for an awesome April fools day
P.S The picture of the nuke is used to show how awesome the prank is -_-
Step 1: Fining the File You Want
Personally for April fools day I use the WTFBoom made popular by YTMND but you can use whatever you want. I also made the sound file available to download if you want.
You can either follow the images or the brief descriptions I gave XD