Because all the people say that the first time is great and after that all people try to reach the same high, but as I already know this information, I can force myself to try only once to see what's the feeling like and then never try again no matter how much I want to reach the intial high.
Would there be any negative side effects of only once? The curiousity is killing me.
What can the feeling be comapred to? Like orgasm?