Here's a link to my gnome village with tips on injecting pranks into your campaign.
Pranks are so common in this village, it can support two joke shops. The downloadable PDF includes ideas on what you can buy there.
And there are plenty of examples of pranks the gnomes play on each other, such as a gnome waking up with half his beard shaven off, or finding himself strapped to the minute hand of the village’s clock tower.
It even includes descriptions of two annual events: Prank Your Neighbor Week and Wizenclimer’s Winter Treasure Hunt.
Without further delay, here it is. It's free: Practical Jokes and Gnome Village
Happy Gaming! -Stolph