Its another way of saying no shit dumbass!!! When did you first noticed!!
Wow!!! look thats a wooden tree?? Your powers of observation are startling.
Being startled so abruptly that you can't stop a fart from escaping.
It happened so fast I got the startle farts!
A phrase used in the mechanics world for turning on an engine and turning it off in under a second.
Stop startling the engine you'll ruin the starter!!
When you forget you have your computer speakers on and one of those audio alerts (from spell checker,you've got mail,Weatherbug, etc) scares the crap out of you. Can also occur when computer is idle but the speakers are on if you have an Aquarium screen saver.(bubbling water)
I was already sitting on a poop knob when I received an audio startle that made me soil myself.