Any public show that is known to suck, but has yet to fail. Often used to describe poor fireworks displays that were nowhere near as good as advertised.
When someone who was once great doesn't know when to throw in the towel, and they keep subjecting the public to their crap, time and time again, diluting their once great reputation.
Craptacular is Michael Jordan's time spent in Minor League baseball.
Did you see Ringo Starr's latest performance on the Daily Show with Jon Stewart? Yes, it was craptacular.
Much like the inverse of a killtacular, this is a word used to describe one's amazing ability to fail so hard at a first person shooter, that they manage to die/lose 5 times in 5 seconds.