From what I've seen, the last word is usually somethin' like....
"AAARGHH!"
"UMPH!"
"GL-GL-GL-GL-URK!"
or
"EEEEEEEEEEYYYYYAAAAAAAAAAAAAAAGGGGHHHHHHHHHHH!!!!!!!!"
(that last one when fallin' offa high places or gettin' cut in two by a table saw, etc...)
- Chongo