This is all about the Bernoulli (ber-nu-lee) Principle. Science says that things like to be where there is low pressure. Here the hairdryers are creating a column of fast moving air and the faster air goes the lower its pressure. So there's a column of low pressure air coming from the hairdryer, and the ping pong ball likes to stay in it. This is a little bit to do with the fact that the surrounding air is also pushing on the ball, keeping it in place.
All of this means that you should be able to angle the hairdryer without the ball falling to the ground, which is why you can pass the ping pong ball to your friend without it dropping - hopefully!
Be very careful with all electrical equipment and always ask permission before you use it.
Do not use the hairdryer on the hottest setting and do not leave it on for too long at any one time.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.