Longman Dictionary of Contemporary English
Wiktionary
a. (context vulgar English) Having an empty bowel; greatly frightened; (non-gloss definition: see usage notes below).
WordNet
adj. extremely frightened; "he was scared shitless"
Wikipedia
Usage examples of "shitless".
The esper grinned savagely, scared shitless and not giving a damn, and then the bomb in his hand went off, blowing the cannon apart.
Part of me wants it again, but the rest of me is scared shitless at the very thought.
President Jones is an ex-general, you know, and the military is still scared shitless of whatever is behind the gates.
You were scared shitless when you heard about Ben Schuler getting shot, and Gino and Magozzi saw that.
Her nonborn adoptive siblings Ellen Gunn and Hugh Murdoch were overawed at her new position of authority, while the onetime bully Gavin Boyd was scared shitless of her until she assured him she held no grudge.
Shaftoe looks out to the right and sees mountains covered with snow and gets scared shitless for a moment thinking maybe they've strayed into the Alps.
And I just know they're scared shitless that someone like you is going to find out.
We were all scared shitless and at the same time still thrilled to be doing what we were doing.
Because, face it, he was scared shitless that shed given up on him and struck out on her own.
It also gave his hands something to do when he was nervous or scared shitless.
All of these Raft dudes, these tough scary homeboys of the sea, are scared shitless of this guy.
I was scared shitless that he'd kill me anyway, so when I heard that the Boulevard-Citizens heisters took some of Benny's money along with the bank's, I shook down stoolies until I got Bobby De Witt on a platter.
Everybody was shivering, and I remember sitting perfectly still because it was warmer that way, and Joey Mantaneo was pushed against me like four o'clock on the D-train going to Brooklyn, and even in the cold he smelled like cordite and rot and piss (and that cordite smell should have alerted me that something bad was crawling toward me), and he had his war name SCARED SHITLESS painted across his flack jacket and stenciled on his helmet like he was military police, and I knew the story about how he got his name -- but he was the only one in Bravo who'd never been wounded or sick, not even an infection when he cut his finger.