"Great Scott!" (Your spoken phrases.)

[quantum mechanic]

For bad stuff: fudgemuffins, hell, damnation, or buggeryshite, depending on social context.
For good stuff: hooray! yay! awesome!
For surprising stuff: Whaaaaaaa? Holy shit! Sacre bleu! Par Toutatis!

 

[Philbyy]

Aside from the occasional 'What is this, I don't even' I tend to go with the standards, a 4-letter profanity starting with 's' and referring to poop, or just 'Bollocks.' I tend to find being brief keeps things moving and leaves more time for a considered response.

 

[deserteagleeye]

"Oh my God, WHY!?"
"AW Fucknuts!"
"Fuckin' A!"-Warriors.
"Of Course!"-Because it only happens to me.

 

[BlackStar42]

"Ah. That's not gone well!"
"Oh for the love of-"
and the all time classic
"FFFFFFFFFFFFFUUUUUUUUUUUUUUUUUU-"

 

[TiloXofXTanto]

"Carps"
"Curses"
"SHIZUKU NI!" (so many people need to just shut up sometimes)
"CARBON!!"
"[insert random term here such as "metacarpal", "Argon", "Archeopteryx" etc]"
...other things, but I can't think of them.

 

[loc978]

I stole my favorite one from a cartoon:

"Holy dammit Christmas!"

 

[CondorBob]

For mild surprise or for the start of a rant, I usually use, "Sweet Christ on a Cross Bun". When something weird is happening, I just opt for "Kinky".

 

[Neo10101]

"Purple" when I just try to say something and keep messing up.

 

[Not-here-anymore]

"Son of a whore!" - Adopted from Frisky Dingo (same with Boosh and/or Kakow). I found that I used this phrase the most during the end of Dragon Age II ._.

I use this a lot, though I don't know where I got it from.
Son of a mother is another one I use. In the right tone, it still sounds like an insult, rather than just a statement.

I like using "What the shit?" as well instead of the usual WTF.

This. Also "shitting hell" instead of the more common "fucking hell"

Cleaner versions include:
"C'mon, really?!"
"Graaargh!"
and "well, frak"

 

[revolutionaification]

Mine vary, often relating to whatever it was that shocked me in the first place, but generally:

"What the shit?!" Used to express confusion/disbelief/painful levels of hilarity. It was particularly surprising when on my first playthrough of Mass Effect 2 I was dropped into a certain pilot's shoes, only to hear him use the exact same exclamation a few moments later. Spooky stuff.

"Bloody Hell/*insert origin of offense here*!" Used in just about every single situation. Ever. "Bloody" just seems to be instinctual.

Also, my personal favourites:

"What is this fuckery?!" Used to express confusion/frustration/all-consuming rage. Usually followed by a grudging, mumbled explanation a few seconds later of, "Freaking/fucking wizards..." Occasionally with a "Always trying to verb my nouns" tacked on at the end.

I swear too much.

EDIT: "Kinky" can also be used as a stand-alone phrase to acknowledge and dismiss something I don't have enough time for, or simply can't form a reaction to without melting my brain.

 

[dakorok]

I say "mmk" a lot, and my standard goodbye is "Have fun; don't die." Sometimes people get offended, but they usually understand I'm being silly.

 

[Forlorn Guardian]

I apparently threaten to set people on fire a lot. It's a lot more playful than it sounds. Hopefully.

 

[TonyVonTonyus]

Tekken! (when I'm angry)
Piracy!
I call rage!
Walish (word I made up. Walish: Noun,adj,verb,adverbe,punctuation: A derogatory term open to interpretation)
Fascism!
Damn Vikings; Burning our women, raping our churchs

 

[thegamermn]

I tend to use "the crap" alot. it's just a slightly shorter version of "What/where the crap" for instance: The crap just happened?
Though some of the others would be "vas val das" which is german for "what is this" orrr "vas is los" which is "what is going on." annnd numerous outbursts in scottish or german accents.

A few of the truly odd ones would be: Son of a biscuit-eating bulldog, Derbefrezhig (a word that, to my knowledge, means something. Usually only heard while i'm working on a computer) annnd "what the flying fart on a firecracker"

 

[Fiz_The_Toaster]

"Holy shit on a shingle!"
I don't know where I got that from, but I say that quite a bit.
"Christ on a Ritz cracker!"
Again, I have no idea.
"AARGH! *unintelligible sounds*"
When words can't fully show my frustration and anger.

 

[iLikeHippos]

"Fucking DICKSMACK!"

"Nononononononono you don't get to do that fucker, I fuck YOU!"

"I sweat to God I'll eat your babies!"

All in a fit of rage.

 

[Chelsizzle]

Any form of 'tits'.

Shit-tits.
Holy tits.
Titties.

And sometimes 'piss on my dick', even though I don't have one..

...I don't know.

 

[Typical Cats]

Holy Zeus!- Oh my god, Holy God.

Yeah, I know.

 

[xdom125x]

"Facepalm" (alongside me facepalming)

I know the O..P. used it as an example:
"Great Scott!!!" ( Still wondering who this Scott guy is).

"[censored]sucking, mother[censored] [insert problem here]". This one is primarily used against malfunctioning technology. I'd estimate that at approx. 95% of the time I use this one.

"I am literally angry with rage"

Sweet Zombie Jesus! (thanks Futurama)

Damn, beaten to my number 1 response.