Shloof

I just read a short story by David Sedaris in his book "Me talk pretty one day". The story is called "Go Carolina" and it's about his grade school lisp and subsequent sentence to speech therapy. I can relate. I too was a lisper. I frequented the dank, dark, unmarked office of the speech therapist in the second grade. I don't remember being tape recorded like Sedaris does, but I do remember those pictures of tongue positions. I hid them like pornography in my underwear drawer cause I didn't want my brother to make fun of me.
Why does the word 'lisp' have an 's' in it? Why does the term 'speech impediment' have so many syllables? Why is the sky blue?
Ttthhhh. I must 'thleep' now.