it's the weirdest thing

Here's the thought I've been pondering since I woke up this morning: How come I can't tickle myself? I mean, I'm a very ticklish individual. It doesn't take much to get me squirming and kicking...a poke here, a stroke there...almost anywhere on my body. But I cannot, for the life of me, tickle myself. Why is that? I know where my "weak spots" are. I know what type of tickling I'm most susceptible to...so why can't I tickle myself. I can poke and massage and jab at myself all day long...nothing. I mean, it takes everything I have not to burst out laughing when the doctor touches me during a physical. I have to concentrate--hard! But I cannot tickle myself. Weird.