This will sound dumb but I accidently put in the key of another car into my 87 rx7 and it worked but now I can't get it out. Has anyone ever done this or is there anyone that can give me some advice?

 

This can happen with any well worn cylinder lock with a similar key shape.
You are going to have to jiggle the key every which way, firmly but not too hard.
A small shot of WD40 might help.

I bet not 1 person in 10 ever oils locks for preventative maintenance.

 

Yep, happens if the locks were not maintained or if they lock cyls are all worn out.

Would not happen if the locks were in proper working condition

 

penetrating lube!!

yeah it happens when they are worn out, if your really worried, you could replace them but that might be $$$

 

I've tried jiggling it in every way possible and used a couple lubes and the key is firmly stuck in. I tried taking out the whole ignition switch but I can't figure out how it comes out at all and the service manual offers no help, any advice?