From Brotato Wiki
Item
Plastic Explosive is an in-game item that can be bought from a Shop or can be found in a Crate. Most Items modify the Stats of the player, and some of them provide additional effects.
Plastic Explosion
Plastic Explosion increases the size of any explosion you cause by 25% per Plastic Explosive you have. It is multiplicative with the base explosion radius of an explosion.
See the Explosion page for a list of Explosion Sizes.