Well, wasn't really scared.
But I just got my 360 back in '08; was new to the graphics, having insane fun, ADHD kicks in, etc.
I got COD4 for a b-day/Christmas present and was playing it on campaign. Hear dog barking, figured it was just the background sound effects I was used to. 5 secs later...... WHAM! Some bloodlusting, hairy, homocidal, canniballistic, bloodthirsty beast jumps on the screen and I go flying!