I know what you're thinking:
"What? Ejecting is what killed Goose! Of course Top Gun warned you about the violence of a failed ejection! How dare you disparage a cinema classic, sir -- I choose you."
"See here, what's all this, then?"
Keep those cinephile pistols in your belt, because we're not talking about failed ejections here: Even when it goes perfectly, ejections are like getting curb-stomped by a wind god.
When you pull the ejection handle, a number of things happen in quick succession. The first is that explosive bolts and/or detonating cord activate to blow the windscreen (or canopy) apart. At the same time, straps around your legs pull your feet to the seat so that your legs aren't torn off at the knees. Next, a rocket under your seat (not a euphemism here -- an honest-to-God rocket) lights off and shoots you up to 200 feet in the air, subjecting you to, in extreme cases, upward of 20 Gs. For reference, at 20 Gs, an average guy now weighs as much as a full-size sedan. This entire process takes about 0.1 seconds. Once you're clear of the jet, your seat separates from you and automatically opens your parachute, a handy feature considering that there's a good chance you'll be knocked unconscious from the shock of ejecting.
They went through a lot of kittens before they figured that one out.