The type MD is talking about is almost assuredly psychological coincidence. Kind of like when a song comes on the radio that you were just thinking about. What you don't realize is that thoughts like that are fleeting and you forget about them seconds after you have them. When an outside catalyst validates the thought, it seems eerie or strange, almost like a sixth sense or a psychic power. Ergo, normal people probably have the thought
(possibly stemming from what cheebs said) that someone/thing could possibly be watching them several times a day. The validation is when you turn and actually catch someone who was checking you out. That gives the creepy feeling that you get.

Same thing with the song example. When I'm listening to the radio and a song comes on that I was just thinking about, I get that "Wow, that's crazy!" feeling. The thing is, I have bits of songs going through my head all the time at different times of the day. If you listen to a radio station that plays music that you listen to, chances are it's going to happen fairly infrequently at worst.

I like the answer flayed, not I'm talking about an uneasy feeling of not being alone when you think you are. I'm talking about feeling the focus of someone's attention. It's a unique feeling in my shoulders, neck and head.

it starts in the shoulders, I usually don't notice it or ignore it. then I feel it in my neck which is when I realize I'm being stared at, I don't look behind me hoping the person will stop. When it goes to my head I have to turn around. I've never once felt it and not had someone staring at me.

im not alone, somebody will speak up so I don't look nuts.

I get that all the time. But, I'm paranoid and very sensitive psychically.

I'm going with this answer.....sounds logical.

Does anyone else's spider sense tingle when they are in danger?

That's the exact description of an animal's 'hackles raising', and that's exactly what I was talking about...When prey is being stalked, this is what happens to them.

Urge kinda proves the point...He's a predator, so he never gets the sensation :p

I know what you're talking about, because I get it, too.

I usually just piss myself

OK

SO you are feeling something, because you can not see this threat or here it or smell it. There has to be some sort of stimulus to trigger a response from the body, that is what my question is. an instinctual response needs a trigger, what's the trigger.

...vanity?

I'd rather people feared me than were attracted to me.
See, in my current situation, fear, I could do something with.
Yknow somethin'?
This one old crazy bitch on the train yelled at m'self, girl, and friend because we were talking too loud and "stealing her personal peace", after having a go at amost everyone else on the carriage. So I'd heard enough that when it came my way I just said that she should leave 'cos she was making more noise than anyone, she kept at it, I just said "get out then", and laughed.
She got up and said "I hope you die you big brute" on her way out
Seriously, I know it was meant to be an insult, but I was nothing but happy on all that, see, it took a brute, but she left.
The brute, gets things done.

That's also, what she said.