Something happens and you panic a little. Or start dreading the future related to the event. Either or.
I was browsing the FNAF wiki for stuff on the newest game. (I'm way too much of a pussy to play it myself.) After a while, I find the background image intensely distracting. After all, nightmare robits do have a way of catching your eye and making it hard to pay attention to what you're trying to read. So I decide to try and find a way to block the background image. Adblock Plus doesn't give me the option. Remove It Permanently just fucks up the page and makes it unusable. So I decide to browse through the source and see if I can edit it out on my end.
After quite a bit of fiddling, Firefox seems to freak out and hang. Can't close the inspector, scroll the page, or exit the application. As I'm reaching for the three-finger salute, Purple Guy wanders onto my screen via some form of scripting magic I wasn't aware of and starts chasing my cursor. Knowing the source material for the wiki, I figure something's going to scream in my face when it catches me. I am now panicking. I instinctively hit CTRL+ALT+DEL to try and shut my computer off. Windows 8 doesn't have a power off option from the CAD menu, so the next best thing: Log Off. I never use it. I didn't know if I'd get shit running right again, but I didn't care. I was not getting a jump scare up my ass!
But things went fine afterwards. Still haven't been back since, though I'm playing with the idea of checking again to see what the fandom's dug up since.