Bobblehead: Explosive in Fallout 76 is one of the Bobbleheads. Bobbleheads in Fallout 76 are items tied to a specific skill or SPECIAL Stat that provides a boost on that specific stat. The Bobbleheads in Fallout 76 are extremely unique for the series due to their stat boosts being temporary rather than permanent. You can find Bobbleheads while exploring Appalachia.
Once obtained, Bobbleheads will remain in your inventory until they are "consumed", at which point they will grant a bonus for a full hour - the bonus matching close to what that item did in previous fallout games.
If you are able to find a second collectible of the same type, you can use it again to refill the current timer, but the effect doesn't stack.
Location/Where can you find Bobblehead: Explosive