“ You find a patch of edible funghi. They taste well and all, no ill effects. UNLESS you consume some beverage, even 3 (three) days after eating it. Then you become really sick with pains, vomiting, all the fancy stuff. As a gift or good meal, it could be a cruel joke or to make sure the heroes spend their time focused on the mission. And the fine soup you had in the inn yesterday could have some in.
(Inspired through a real-world fungus. Was really used to cure alcoholism.)”
“ The Yugzhee, or 'hedgehog-people', guard a great, secret treasure inside their giant burrowed lair. The mysterious Wall of Keys, a 12'x10', foot-thick, cold-iron, 'wall', upon which, on iron hooks, hang 100 ornate iron keys of all shapes and sizes. Each key opens some heretofore un-openable barrier, door, or gate, in the particular game world of choice.
The PCs have come upon a great boon, except for the fact that the keys cease to function properly if separated from the iron wall for more than a few minutes. Higher level characters will be able to figure out how to take the wall 'with them' via magic. Lower level characters will have to get creative.”
“ Bag on a Stick
Very simple gag but a great one, since it can be used multiple times over, even in the same adventure. Great for tribal natives gone restless and humanoids, but anyone can have set this up. Just what the header says, a simple bag over a stick stuck in the ground or floor.
As GM you can place the bag on a stick anywhere, in a floor crack the heroes have passed before, outdoors in a clearing or path, or at the edge of the PCs' encampment the following morning, what have you. Place anything on the stick - a coiled yellow viper angered by the bag removal, mini crossbow w/poison, transdermal hallucinatory drug dusted on the bag, yellow mold colony, an NPC ally's head, a weapon, scroll tube or satchel, what have you.
The idea is to build tension and/or stall for time/distract the party. Provided it's used properly, you'll be amazed at how paranoid players will get from this simple gag.”