"Rifle" Versus "Riffle"

An interesting Q&A from Grammar Girl.

Q: The other day on Twitter I said I was going to riffle through the medicine cabinet looking for something to soothe a wicked headache, and someone corrected me saying that I was actually rifling through my medicine cabinet. My headache went away, but my curiosity about these two words didn't.

A: Both "riffle" and "rifle" mean to go through something, but when you're riffling you're hastily flipping through something--such as book pages--or shuffling cards ("riffle" is thought to be a blend between "ripple" and "ruffle"), and when you're rifling you're searching frantically or ransacking, usually meaning to steal something ("rifle" is from the Old French word for "steal or plunder"). Indeed, I meant to rifle.