So after the comic gained notoriety, a lot of people started doing parody versions of it. Evidently this became so widespread that the basic positioning of the characters became a meme itself, so you could reference it with nothing but some lines. The lines on the gun.

At the heart of it all though, this is just a guy drawing a meme on his gun.

Ahhh, okay. I was trying to figure out how it was connected to mass shootings or…anything, really. I guess my error was looking for a deeper meaning in the first place. Thanks!