Thump-Thump is a unique grenade rifle which has the extended range of a barrel extension mod found in its common counterparts and enhanced AoE radius. It also has 30% faster attack speed, 0.5 lower weight, and is 25% more durable compared to a standard grenade rifle. It also has a unique texture and the words "Thump-Thump" scrawled on the side with an arrow pointing towards the muzzle. There is also a drawing of an angry beaver with red eyes holding a rifle on the stock.
Thump-Thump can fire a total of about 620 standard rounds from full condition before breaking.
Nellis array - Inside the building, south/southeast of the generator switches during or after the quest Ant Misbehavin'. It is next to two broken generators, by a skeleton.
If the Boomers are killed for Mr. House or Caesar's Legion before obtaining Nellis array building key by Raquel, Thump-Thump cannot be obtained. The building's door is unpickable and can only be opened with the key, but it does not appear on her body if she dies.