The Shamblers from The Last of Us Part 2 had big explosive bums in an early build of the game.
As spotted by TechnClub, Matthew Gallant, lead systems designer at Naughty Dog, shared a clip of what appears to be a test environment with Ellie in combat with a few Shamblers that have a very different appearance to their look in the final game.
As you can see in the video below, the Shamblers' bums were bright and appeared to explode and exert a gaseous acid.
The Shamblers were introduced as an alternate fourth stage of the Infected (the other being the Bloaters) in The Last of Us Part 2. They spray acid near the player and are very strong, with the ability to take massive amounts of damage.
In Last of Us lore, the Shamblers came about because of heavy exposure to water in the rainy environment of Seattle, while Bloaters develop in dry environments.
I quite like this early build of these monsters, primarily because I'm sure Ellie would have made a silly remark about their oversized bums, likely alongside some expletives.