*put a coaster on the edge of the table and flip it up with the back of your hand and catch it in the air; then do it with 2 coasters stacked, then 3,4,5,.... etc
(i can get 43 coasters)
*open bear bottles creatively
*fill up a glass of water until the very edge, place a coaster on top, hold it down, flip the glass upside down with the coaster sealing off the water, then gently release the coaster and you'll see it wont fall down !!
*get a lighter, make a fist, "inject" lighter gas into your closed fist, then ignite the gas (takes some time to fill up your complete fist) and you'll create a small fireball :)
*get somme cotton props, or a piece of cloth, wrap some yarn around it so you create a firm cotton or cloth "ball" (diameter of a marble)
then pour some lighter fluid over it so its saturated, then light on fire and play with it in your hand (be carefull not to burn yourself, you can hold it in your hand while it burns as long as you keep moving it around (check youtube for fireballs)
*you can stab through a beercard (coaster) with your index finger, just do it fast enough or you'll hurt your finger, show it to people then challenge them to try it too; most of them will do it too slow and hurt their finger
*etc
(i'll think about some more....)