Water Gun Location?

[Grammar Nazi]

I've come across a few things that LOOK like the water gun and people say they ARE the water gun, but I can't loot it. There's even a key (9) in the options menu that's used to equip the water gun.

The first place I found what looks like a water gun is after the mental echo where you have to hide behind a chair. I couldn't loot it.

The other time I found it was going through a level (Maybe the eighth or ninth levels) and I found it on a chair. Once again, I was prohibited from looting it.

Any ideas?