The obvious combination of both "shit" and "damn" to make the ultimate expression of surprise or shock, not generally cursing one's fate, just being freaked out or surprised.
"I'm...actually a dude."
"SHITDAMN! That explains my anal pains!"
cocksucker, pussy asshole cunt. motherfucking dirty whore, shat onto my lunch. Piss cunt damn bitch suck my dick Jesus harold christ, shit bitch cocksucker goddamn motherfucker pussy asshole cunt!
Guy 1: Im gonnasing Guy 2: wut?
Guy 1: Fuck shit damn bitch
Guy 2: oh... fuck
Expressive phrase used when one four-letter swear word just isn't enough. Used most commonly in the given order, but may else be used as shit fuck damn.