User blog comment:PeaShooter/Even more Challenges/@comment-4647769-20120107002748

You'd need a Magnet-shroom to get a Jack to eat your brains; otherwise, it will explode before it can. It may get far enough to trigger your Lawn Mowers first. I'd say the easiest way to do this is on the Vasebreaker level "M is for Metal," though I haven't done this. I put this comment to tell people who are having trouble with this one how they should go about getting it.