The phrase lock them up and throw away the key is a long-standing English idiom for imprisoning someone forever, and online it has been shortened into a reusable reaction clip. As a meme sound it spread through short-form edits and soundboards where creators needed a quick, exaggerated judgement for cringe moments, bad opinions and obvious fails. Its appeal is that anyone recognises the meaning instantly without context, so it still works as a punchline even when the original clip that prompted it is completely unrelated.