I don't know why, but I have this weird fascination watching people who are totally engrossed in something. Usually they're reading a book or doing work, but I just can't take my eyes off.
Also, wearing a T-shirt I got for free for the first time. I don't mean like a gift, but a handout at some place. I don't care what the T-shirt says or if it recommends a cause I don't support, I love standing out from the crowd of other young people all wearing Hollister, American Eagle, or (hopefully not) Hot Topic. It's like it defines exactly where I was at an exact date, thus defining a portion of myself.