long words are always suspect... especially the fear of long words (only one p btw), which is only ever used in this context and which is essentially comprised of three redundant prefixes. a long word can be reasonably called "sesquipedalian;" literally "A foot and a half long." adding two more things meaning "big" doesn't help much.
lisp, yes. stutter also.
whether or not pneumonoultramicroscopicsilicovolcanoconiosis has a hyphen is debateable, because again it is only ever used as an example of a big word. as i remember, though, it has a bit more of a reasonable background story.
so if we're going to let these through, might as well let chemicals through:
sodiumÂÂmetaÂÂdiaminoÂÂparaÂÂdioxyÂÂarsenoÂÂbenzoeÂÂmethyleneÂÂsulphÂÂoxylate.
or how about
this one. (Scroll down)