Whose parents put one of these on the phone to keep you from using it and running up the bill?

I remember these - I'm old !

To get around this, you lifted off the handset and tapped the two little 'buttons' (like morse code) for each of the numbers - It worked !

(Incidentally, Hannibal Lecter does it in the 2002 film Red Dragon)

smart, but i found a much worse invention:
imgflip.com/i/6ccj4l