This Idea was dreamed up as a solution to a real problem, but since anything can be mis-used, and since I couldn't find a Category appropriate for the intended purpose, the "Prank" category will have to do.
Consider a Finger. It typically can be moved various different ways. For this Idea, we only
need the motion that is used when it presses a button.
So, the device is a small box containing appropriate electronics and a battery, and a small motor to move the attached Finger in a button-pressing way. On the outside of the box is some sticky stuff, appropriate for easy attachment and removal of the device to/from somthing else.
Now consider a "Secret Santa" (link). One way to do this is to leave a present on the door-step, press the doorbell, and immediately start running very fast.
No more! With the Remote Controlled Finger, you attach it to the door area near the doorbell-button, and walk casually away. THEN you press the button on the remote-control that activates the Remote Controlled Finger, which in turn presses the doorbell-button.
You can even use a chain of these things, if you really want to be far from the scene, when you press the button on the remote control --the Finger it controls presses the button on the next remote-control (which of course is tuned to a different radio frequency), which activates another Finger that pushes the button on a third remote control....
In terms of 'prank', the Finger might not be so large as to be immediately noticed. So the victim opens the door and sees nobody there. Immediately after the door is closed you press the remote-control button again! The Finger activates the doorbell again, the door opens again, and still there is nobody there....