I find it ironic that someone with a speech impediment talks with a "lisp". I can barely say "lisp" without a speech impediment.
I remember when I had an audtion for a play, I tried nine attempts to conceal my lisp, my last try was a very tenth situation.
<iframe width="420" height="315" src="http://www.youtube.com/embed/l3KIxzCqYqM" frameborder="0" allowfullscreen></iframe>