Among Us

EDIT: As pointed out in the comments, Freeplay seems to be gone and was replaced by Practice. I'm not able to check myself if Practice works for this achievement using the below method, feel free to try yourself, but if not then sometime around the start of May 2023 this guide no longer works. Use Alumejr's solution down in the comments if this one does not work.

I managed to get this achievement while in Freeplay instead of boosting or in an actual game using the same method you can use to get the "H U N G E R" achievement and others:
-Start or join a lobby for an online game (for me I went into a Hide N' Seek game but I see no reason as to why a normal game wouldn't work also).
-Wait until after the game starts and you're able to move around before quitting out of the game, just in case.
-Go into Freeplay (I went on Skeld) and use the laptop to turn yourself into a Shapeshifter.
-Walk over to one of the dummies, shapeshift into them, and kill them. Achievement should pop soon after.
Did this on 12/9/2022 right after updating my game, I'll update this if or when it gets patched, happy hunting!