Eek! My Kittens are CRAZY!

So I finally picked up my two new kittens tonight. They're super cute, but I'm a little worried they're going to become brain damaged from running into my walls.

They've been chasing each other around non-stop -- running into my furniture, jumping on top of my furniture, knocking each other off my furniture... A couple of times they've jumped about foot straight into the air and one even did a couple of backflips.

I still haven't named them - so for now I'm going to call them the light one and dark one. (Their names are technically Janis and Aretha, but I'm not crazy about those names. Mainly because I want to say Urethra instead of Aretha and that's just gross.)

The light one has the extra toes and seems to be a little more fearless. The dark one is more nervous - she's a bit scared of me and keeps hissing at her new toys. 'Cause that ball of paper might really get her!

I'm almost afraid to leave them alone. What if they hurt themselves? I've posted some pics (as you can see - they're both in attack mode!)