Ignition key

hey hows it goin. i have a small simple not really a problem but a question. i havea 99 jeep wrangler straight 6. when i turn on my jeep with my key...right after i am able to take out the key from the ignition and keep driving. can anyone explain why and how to fix this

before I took it all out, and went to a push button ignition switch, I could do the same thing with my 93. I also had a chevy truck that did the same thing.
basically the inside of the key cylinder, and posibly the key, is just worn down enough to allow the key to come out.
the only fix that I know of would be to replace the key cylinder.

Chances are your key is worn out.