Used a boost to get through!
Difficulty: Extremely easy
The word "peppy" is an adjective that means someone is lively and high-spirited.
Use either the Lawn Mower, Gardening Glove, Mega-Perk, Zombie Zapper, or dynamite boost at least once in the level. They are very helpful, so you may get this achievement without intentionally trying to get it. On harder levels, you should be using boosts every time to get through a level.