91 Honda blew out spark plug

Yep - I'm experienced

1. if you mean that the plug disintegrated and part of it is still in there, i'd have to ask what brand of plug it is so i can never buy one like yours.
2. if it simply unscrewed and blew out, that's not usually so much of a problem - they can often simply be screwed back.
3. if the head threads stripped, you can helicoil. it's a pain, but easy enough to do with the right tools.

if it's #1, how much of the plug is still in there? if it's just the metal outer, you can unscrew it with an easy-out and simply replace the plug. if it left part of the core in there, the danger is the core dropping into the cylinder. if that happens, you'll have to remove the head. if you can post a pic of the plug remnant, it will help us advise better. tinypic.com is free.