Naked and Poopy

So now I am turning to the less "religious" and more human aspect of my life. My life is surrounded by Naked an Poopy kids! AAAHHHH! You may think that this is just a generalization, but no, they are really naked and poopy. My 2 year old has decided that she doesn't like clothes, and no matter what I put on her, she manages to get it off. And, if there is something a little squishy in her diaper to play with and smear all over - well that's just a bonus! I have been told by many - many people that she is most likely ready to potty train. Really Sherlock?! I hadn't picked up on that one, and I am trying but it isn't quite going as easily as you would think. However, unless I do absolutely nothing in a day but plant my eyes on her, she is bound to have her fun at some point.
In addition, my 4 year old has decided that if his sister is naked, well then he should be too! Nice logic, often after doing the dishes I go to check on them and find their little naked behinds running around and laughing! I have tried everything, spanking, time outs, loss of privilages - but nothing is working. I have actually printed out the application to Super Nanny and am moments from filling it out! Now my son has started pooping his pants again - 2 days in a row! I am not sure if he is having stomach issues (it isn't loose movements) or emotional, but he won't discuss it. Instead he tries to hide it! Yesterday he hid his underwear under the step stool and tried to tell me that the poop smeared all over the toilet was from his sister - even though he was standing their - brown handed! I don't get overly mad, I just asked him what is wrong or what happened, but he won't answer, he just changes the subject - AHHHHHHH!
I don't know what I was thinking having a 3rd! I am out of my friggin' mind. When I was at my OB appt. a few days ago and she asked me if I felt the baby moving. Yeah right I said, who has time to even notice that I am pregnant?! I know this is most likely normal, but it is abnormal for me and I am losing my mind!!!!!