You automatically are trusting because not only is the person a friend, they are so incredibly gifted that you know someone is going to be able to hit the ball back to you across the net. ↗
The main prank that we play with props is for people's birthdays. The special effects people will put a little explosive in the cake so it blows up in their face - that's always fun to play on a guest star, or one of the trainees or someone who's new. ↗
It's changing a bit, but the thing in LA is everyone is either in the industry, or knows someone who is in the industry. So, they don't let on that they recognize you, that's what I've found out. ↗