Okay, so I want to know what this feeling is, what's causing it and why....?

I watch maybe 3 times a week and of course jerk off to it. I have a particular interest in Sasha Grey, being that she is the problem. Whenever I watch her I get a weird feeling. It's like adrenaline floods my whole body and my hands start to shake uncontrollably, my legs become restless and I get a f*ckin' rock hard . I don't know if I have a subconscious crush on her or what. When I watch other stars I get a normal hard-on, as in just another girl. With Sasha Grey it's like I've been f*ckin' supercharged from a car battery, thus giving me a sh*tload of adrenaline. Please help me understand this.