For a riot, try this! In T: DS, go to the small hammer church above the graveyard. You know that elevator that goes up from the graveyard to the church? Ride it up, go out into the hallway, get the guards to chase you to the elevator, and jump up and down in it. The guards will get right next to the elevator, but not actually on it. Now you can hit the button, sending the elevator down. The doors will close behind the guard, causing him to fall off the ledge and land on the bars on top of the elevator as it is going down. Now the ragdoll physics take their toll and the result is absolutely hysterical. I've seen the bodies flip through the bars and land in the elevator.

You can have so much fun with the physics in TDS and invisible war. :)

Also, try throwing objects at friendly AIs in Deadly Shadows. I laughed so hard when the guard told me not to do it again and I did and he drew his sword and came after me! AWESOME!

Turning the city in Thief Deadly Shadows into a deathmatch by randomly knocking civilians out and leaving them in plain sight is also a hoot. Guards, Hammers, and Pagans, Oh my!