from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Vulgar Slang Extremely frightened.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Having an empty bowel; greatly frightened; see usage notes below.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. extremely frightened
From the reflex of involuntary defecation that can result from extreme terror.(American Heritage® Dictionary of the English Language, Fourth Edition)
From shit + -less. (Wiktionary)