FWIW, I got the joke right from the start. Guess you had to be a Diablo player. 
And amusingly, there used to exist a bug such that Black Knights were actually the *hardest* "cans". They have AC 125, and the other three types of knights have AC 130 and 135. But thanks to Blizzard programming wizardry, AC was a signed single byte which overflows at 127, so AC 130 was actually AC -125.
I was very much aware of this bug back in the day; the other three types of knights could be auto-hit with literally any weapon, but Black Knights required a whoppingly high ToHit%. It was fixed in patch 1.07, IIRC.

And amusingly, there used to exist a bug such that Black Knights were actually the *hardest* "cans". They have AC 125, and the other three types of knights have AC 130 and 135. But thanks to Blizzard programming wizardry, AC was a signed single byte which overflows at 127, so AC 130 was actually AC -125.
I was very much aware of this bug back in the day; the other three types of knights could be auto-hit with literally any weapon, but Black Knights required a whoppingly high ToHit%. It was fixed in patch 1.07, IIRC.