Have the PCs rping Orcs or Goblins or some other race that normally exists only as things to cut up with swords.
The PCs accidently start a fire and are caught by the local law enforcement. Since it was accidental, the punishment for the PCs is to fight the fire. Providing they can put it out before it burns down the town, they will not face any further punishment.
A ghost is haunting someone with a secret-it\'s not that he murdered the person that became a ghost, it\'s that he went into hiding with a new identity to avoid being murdered, whilst the ghost wants him to join her in the afterlife. The ghost is getting stronger and more dangerous each day. Enter the PCs.
A festival once a year where almost everybody gets drunk-indeed on that day it is a religious commandment to get as drunk as possible.
A lizard race that is basicly Good rather then Evil, is being attacked by evil humans that want control of their river.
A wizard has cast a slow action freezing spell upon a PC. The air gets colder around the PC by one degree a day. If the spell is not broken within a few weeks the PC will freeze and die.
Within a kingdom the prince or princess has died or been killed and the Queen has been driven half-insane with grief.What if one of the PC's was mistaken for the dead prince or princess and not allowed to leave? There would be advantages in accepting the role, but would it be worth it?
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.