Stupid? Or Crafty?

(I work overnights stocking shelves for a major retailer. While most stock comes in boxes, some items, such as clothes and craft supplies, come in plastic bags. Items that come in plastic are placed in gray containers and are put on pallets with the boxed stock. At the end of the day, we are supposed to take the containers to the back. Once there, we place them in the slot that has the same number as the one on the container so they can be reused the next day. I have been stuck working with an employee who is known for not being the brightest. One night, I notice that he just leaves the containers in the back room without putting them away, leaving me to do it for him right before our shift ends. So, the next night, while I’m making labels for all the overstock, I spot him pulling a cart of containers and decide to ask him about it. Keep in mind that this is not a new employee and the container policy has been common knowledge amongst employees for years now) 

Me: “Hey, [Coworker #1], you know you are supposed to put those away when you take them to the backroom, right?”

Coworker #1: “No! When did we start doing that?!”

Me: “Since always. You just have to put them in the spot that has the same number.” 

Coworker #1: *pauses for a moment and says nonchalantly* “Oh, okay. I’ll just leave them back there and you can figure it out.” *walks away*

(I am dumbfounded. Luckily, our manager is within earshot and tells me he will speak with him. Later, on my break, I try to vent my frustration with another coworker but he interrupts me)

Coworker #2: “Are you talking about [Coworker #1]?”

Me: “Yeah, how did you know?”

Coworker #2: “Because I caught him yelling and whining in the backroom and I had to help him put the containers away because he couldn’t figure it out.”