Might be too late but this is funny!
3. Hijack Firefox with the Total Confusion Pack Extension (Enabled on April 1st Only)
Your victim use Firefox? Install the "Total Confusion Pack" Firefox extension, which enables the following "features" on April 1st only:
Two Steps Back: Make the back button go back twice—not every time, but only on random instances.
Rick Rollr: Switch out 2% of the video clips your victim watches with the infamous Rick Astley video.
The Devil's Inbox: Make the number of unread email in your victim's Gmail inbox exactly 666.
Highs and Lows/Sarcarsm Enhancer/For real: Add LOL, *sigh*, "for real," "Whatever" and various other commentary to web page text.
Watch it: Make it look as if the page was loading forever. (Now this is just plain mean.)
Download the Firefox Total Confusion Pack here.
Firefox Pranks!