The Mega TNT Barrel is an item that is found in Donkey Kong Barrel Blast. Specifically, it appears out of Blue Balloons.
When used, a TNT Barrel will automatically appear above each race besides the player who uses it. They will all drop at the same time, temporarily hindering everybody for a moment. Although Kremlings get an extra effect from most items that appear out of Blue Balloons, the effect is not altered no matter who uses it, Kremling or Kong.