From Calthine on the EQ2 Forums:
April Fools Day marks the Highest of Silly Days for the Bristlebane Day celebration. Three quests are only available on this day (one is new), given by the sphinx Imenand just off the dock in the Enchanted Lands. Test your brain by trying to solve his many riddles and take a gamble at your choice of house pet rewards.
If you’ve been waiting for a Berry-fed Bovich since last year they’ll be available on the Marketplace for 2250SC. The winged version is available for 2950SC. [Editor’s Note: It was available last year for a heart-stopping 5,000SC]
In your travels you may have noticed bunnies all over Norrath. Today, and only today can you collect the silly wabbits and earn four Bunny Achievements! The 500 bunnie achievement was added this year. [Editor's Note: The rabbits on the level 95+ Isle of Refuge zone are for a different quest.]
Players can also harvest from the Jester’s Superior Gardens on this day, which are found in Enchanted Lands. These gardens give harvests from every holiday event that has crafting, so be sure you have a lot of backpack space to spare! Those wanting to sneak in some mid-year Frostfell crafting can do so as well.
The Highest of Silly Days starts as soon as it’s April 1 in Pacific time, and goes until 11:59pm PDT on April 1st.