Take this story for example.
Back when I was cool and working as a Microbiologist, I was sitting in the computer chair with my back to the door to the lab, talking with George, the also cool intern. I don't have any recollection of what we were talking about, probably Community, since that is what we always talked about.
Anyway, Ben, who worked as a Formulator, loved to scare me. I'm pretty sure that it was one of his favorite hobbies and past-times. He, very sneakily, walked through the lab door and crept up behind me.
Let me just clarify that George knew that a scare was imminent and he did not do his duty and warn me! I may or may not still be a little bitter about it.
Well, Ben gets right behind the chair, leans over, and just says, "Boo." right into my left ear.
I. Freaked. Out.
Screamed.
Gasped.
And flailed.
In an attempt to get myself away from my attacker, I flung my body to the right and tried to counterbalance the weight shift by swinging my legs to the left. What I failed to realize was that my legs were right underneath the counter. When they swung up they whacked the underside of the counter, very hard.
I was in immediate pain and my heart was still racing. Naturally, all Ben and George could do was laugh. Of course I laughed too because, I mean, who couldn't laugh at how outrageously ridiculous my reaction was.
If you look closely, you can see where my leg met the counter.
As you can see I ended up duct taping an ice pack to my leg so that I didn't have to hold it and try and work. Luckily, I wore purple that day and the duct tape didn't clash with my outfit! Either way, I still had a nice sized welt.
So, my advice to you is to be more like a ninja and less like a spaz. Trust me, ninjas probably don't get startled like that and end up with bruises like mine.