Charlie just spit on the floor

Why do 2 yr olds do the things they do? They are funny and weird little creatures. For instance, just now, my son, Charlie just leaned over and spit a glop of spit on the floor. He hadn't been eating, he hadn't gotten dirt in his mouth. He just spit to spit. He is odd. And today he was hilarious as he relayed the incident of him getting hit in the head by a swing. While rubbing his own head he says, "Ben...hurt...hit me...swing hurt me...Ben did it...hurts..." Sort of sounds like Yoda when he talks. Cracks us up. Let me mention something now that does NOT crack me up at all! I lost it today. Went bizerk yelling and freaking on my children. Apparently a person can only go so long busting their bum cleaning up after people who when you ask for some help say things like, "I'm just so tired, and I have a headache," right after they get home from playing at their friend's house all day. Apparently a person SNAPS when they have to pull a bunch of folded clothing out of the dirty laundry basket. Apparently a person goes over the edge when they walk into the newly mopped kitchen to find that someone has left sticky juice all over the entire kitchen floor. Apparently a person reaches the breaking point when after asking her children to help out by cleaning up the yard, she continually finds them in front of the television, while she has been upstairs changing 7 sets of bedsheets! finding an amazing amount of crap under her kids' beds and finding an amazing amount of expensive crap under her kid's beds. I was saying things like, "I'm going to end up in a nuthouse! You children have no respect for anything! What am I, the MAID? All phrases used by my mother numerous times, phrases I swore I never would use. I get my mother so much more now. So, when I settled down a bit, when I had everything in better order and some apologies from some kids, I also apologized to them. But my apology was for the yelling, and I made sure to tell them that it was for the yelling, but not for the being angry, because that was totally warranted considering the way they were reacting, or really NOT reacting to my requests of them. And I am sorry. I don't want to yell or be "a yeller" and I have been pretty conscious to try to remain calm in frustrating moments for the past year or so...but everyone has a limit and I guess I hit it. I pray that I can stretch the limit out a little longer each time. It would be unrealistic to pray for total calm. I'm not that naive.