Well, Consuelo, here's a bit I googled:

"Up to par, Katie bars the kitchen signs but not me in"
There's an old saying "Katie bar the door". It's used a lot in the south meaning, "something unstoppable [is coming]". [gerbil] * 'Katie bar the kitchen door' is a southern term that meant you better watch out. [Stipe, on AOL] * It's been suggested that this song might be related to Stipe's sister's experience teaching deaf children. (Consider also "I'm the sign and you're not deaf.") Therefore, the "sign" in question might be American Sign Language. [Chris Piuma] * "Up to par" means "good enough". [Chris Piuma

http://www.flim.com/remlafaq/murmur/sittingstill.html

And that's just theory, so mebbe you'll get some more theories on this today.

Best regards,
WW