Snap, crackle, and pop are also terms for later derivatives of displacement -- or, to put it in simpler terms, the rate of acceleration of acceleration of acceleration of acceleration... and so on.

Okay, that wasn't simple enough. Let's start over. When we look at an object sitting at rest, we determine its position; this is the 0th derivative of change. When we look at a moving object, we measure the speed in terms of velocity; this is the first derivative of change, the change in position over time. And then, we measure the rate of change of velocity, which we call acceleration. You can also look at the rate of change of acceleration; this is called jerk, and is the third derivative of the object's displacement, i.e. it is the rate of change of the rate of change of the rate of change of its displacement.

You can keep going; the fourth derivative is called the snap, the fifth is the crackle, and the sixth is the pop. The snap is sometimes also called the jounce, but usually people conform to the cereal-based names, as Kellogg's marketing has been quite effective.

And we can keep going; the seventh derivative is sometimes referred to as lock, the eighth as drop, the ninth as shot, and the tenth as put. However, after pop these terms are mostly just there for fun and wackiness. In fact, anything past jerk is somewhat informal, with snap/jounce being infrequently used, and later derivations primarily being used to illustrate the concept that acceleration is infinitely analyzable, and of course, as wacky science factoids to entertain the masses.