As a veteran DM of over 20 years, I can confirm that this will indeed kill the party (and game)

no no no don't drop monsters at or on them let them believe their alone let them see things in the corner of there eyes. say "the floors of the dungeon are clean as new" if they suspect abort until their guard is down and BOOM gelatinous cube or whatever you want to kill them

"Total"

The T stands for Total, not Team. And also, if the party are 'annoying' or 'murder hobos',
you have likely framed something wrong as the DM,
Maybe that particular group is better off playing a video game together.

The Terrasque has a baby.

Astral Trolls control their breatheren in a epic war waged versus their favorite bar for reasons of "an express way".

The Modons perform a mysterious dance which teleports two planets to collide for 'insert x reason'.

Gelatinous cube drops, everyone dies.

tpk stands for 'total party kill'

Those who say "Just communicate with your players" are seriously ignoring some major things about players. If it gets to the point that you are about to TPK, you have already tried that. You have thrown shit at them, you have killed problematic characters and they just made a new one with different or the same problems, there is so much going on beyond "talking" to your players.

I like it. Thanks. Will use it in my next session. My players are level 3 already. Do you think this method still works? /s

I'd have imagined this was an embittered response to receiving such treatment from a GM.
But I agree with the others, this is a pretty roundabout way to communicate to your party that the campaign's been hopelessly derailed.