Tape a hidden walkie take on your dog, have a friend walk your dog around a park, and go up 2 people. Start talking through the takie.
Chew on a pencil until its covered in bites, then give it to your friend and once there holding it, tell them you found it and they can have it.
In October, wear a creepy Halloween costume and stand by side of a road or sidewalk and pretend to be a decoration. When someone walks by, wave at them. (or chase after them) Get a friend to film their reactions!
Tie your sibling or friend to a chair and see how long it takes them to get out with no help from yo.
Get a friend and a marshmallow gun, and see if you can shoot marshmallows into each others mouth.
Go up to a stranger and try to and try to convince them that you were their imaginary friend once.
Have a better idea for this list? Send it on in!