Separating each spinal vertebra is a disc. Its fibrous outer ring holds in a jelly-like material. Because of the way a disc attaches to the spinal bones above and below it, it can't actually "slip." However, a disc can bulge, tear, herniate, thin and collapse. But it can't slip.
How do you "catch" a cold?
Simply lower your resistance by avoiding the proper rest and exercise, eating lots of sugar and junk food, putting up with emotional stress and neglecting your nervous system by avoiding your chiropractor. You won't have to catch a cold because it will catch you!