You can find the Lawnmower in the Southern part of Up-down-Uptown, on the road. It's difficult to miss, just explore the area and you'll find it.

How do I use the Mindblower?

Once you have done the quests for lawnmower "bling" you are able to use the mindblowers. When you activate each mindblower, you effectively become the lawnmower & need to drive to the nearest bodyguard to get rid of it by exploding. You can then access the area the bodyguard was protecting.

Where can I find old cools?

Olds Cool is a boss zombie in Plants vs. Zombies: Battle for Neighborville, and the final boss of Town Center. He is a Disco Zombie with a bigger afro, who pilots a giant disco ball machine.