Men can achieve intense pleasure through prostate stimulation. The general idea is to apply pressure to the prostate. The prostate is a gland which is part of the male reproductive system. It's primary function is to produce semen which nourishes sperm for their travel out of the male body. However, the prostate also contains a large amount of nerves and during sexual stimulation can cause pleasure similar to what women experience when the female g-spot is stimulated. Most notably, by applying firm pressure to the prostate during orgasm, men can achieve a mind blowing orgasm unlike any that can be experienced during normal intercourse.
How to go about this is a bit more of a touchy subject. Applying pressure to the prostate is most easily achieved through the anus. This can be a hangup to many straight men as inserting something into the anus for sexual stimulation is something viewed as a homosexual act. However, there is nothing to fear as enjoying anal stimulation does not make one gay, enjoying sex with men does. Well, perhaps enjoying sex with men does not make one gay as it does not necessarily (but usually does) imply an attraction, but that's a topic for another node...
It is probably best for men to experiment with this alone while masturbating. The best way to apply pressure to the prostate is with your finger. The best bet is to cover your finger with a condom or other protective medium, and lubricate the area extremely well. When the finger is inserted, curl it forward towards your front and apply pressure to the anal wall. When you hit the prostate, you will know as it will feel good when the pressure is applied. You may also apply pressure by the insertion of a large object up the anus, however many men may find this quite uncomfortable.
While this may not appear to be a very exciting thing to do, it is one of the few ways for men to experience earth shattering orgasms.