ATF 'r Us is a weapon store run by the ATF, located at the East side of the Paradise Mall. Some of the weapons sold at ATF 'r Us include the Pistol, the Shotgun, the Machine Gun, Grenades, and the Sniper Rifle. There is a locked storage located at the back of the store, which can be opened by shooting a switch on the wall. Shooting that switch will also open the cages behind the counters. Cans of gasoline, Rocket Launcher combustible and Napalm can be found in that area. A door nearby leads to a meeting room with lots of doughnuts on the table.
The name might be a play of the phrase "After us", which often means the police, military forces, or any other authority is looking for you. It's definitely a play on the real-life store Toys 'R' Us, which is often parodied by other games, movies, or generic social groups or dads.