In bowling, a single pin that remains standing after the first throw, not allowing a strike. The pin is considered a 'devil pin' if this happens multiple times, no matter how good the bowler.
Jack: "Did you see that?! I hit the pins perfectly and that damn devil pin is STILL standing!!"
Kelsey: "I told you that one pin was the devil pin!"
The Devil Pin is the right-most back pin when it's the only pin standing after the first throw, especially when it causes a missed spare. This pin is the hardest to hit using the hook that a typical right-hand player throws, hence the name Devil Pin.
I missed another spare -- that Devil Pin gets me every time.