As it sounds, there are a few circuit breakers throughout the body that when pressed with enough force they manually prevent ejaculation. Learning to use them properly takes a little time, but once you are familiar, these can provide the ultimate emergency safeguard against any ejaculation before you are ready.
MILLION DOLLAR SPOT
A long time ago a Tantric Master named Lu the Immortal discovered a place on the body that when pressed with adequate force would manually delay ejaculation for as long as required. He ordered his disciples to guard this secret closely, and made them vow never to reveal it to any outsiders. The legend goes that around the turn of the twentieth century a wildly wealthy American, (who will go un-named) was on a journey in Western china, home of the disciples of the legendary Lu the Immortal. He had heard of their abilities, and sought to learn the ancient ways in order to improve a modern problem of his own.
Most of the masters he encountered were taken aback by his loud and abrasive mannerisms, and if they told him anything, they spoke only in intentionally vague and mystical language. In one of these sessions in particular, a younger master (and by younger I mean in his early 60's) was repeating through a translator the fable of the cobra. "While coiled, the cobra is quiet and poised. But when he strikes he becomes vulnerable." The American had simply had enough. In a wild outburst he exclaimed, "God, Damnit, isn't there just some spot I can push!" A very old and wise master who had been sitting in the corner of the room broke into a very uncharacteristic smile. This caught the American's attention.
In perfect English he spoke. "There is a spot, that if you push it, you can delay your ecstasy for as long as you wish." The American knew how to spot a bullshitter, but saw nothing but truth in the master's eyes. Intrigued, he asked in his most polite and beseeching voice. "Well where the hell is it..." The master replied, "I will tell you. for a million dollars." The American laughed, and then stared back into the long-beard's unflinching eyes. "Alright, I'll pay it." According to the story he did just that. In that place a great temple was built, and for the first time ever, Lu the Immortal's secret was revealed to the western world. The "million dollar spot" is in the area you might have heard called the 'grundle' or the 'taint', which is that strange stretch in between the scrotum and the anus.
The optimal pinpoint to push varies slightly from person to person, so start somewhere dead in the middle and adjust accordingly. Sufficient pressure on this area preceding ejaculation will prevent the semen from shooting up the vas-deferens, and will cause it to harmlessly return to the source, allowing you to continue lovemaking at your leisure. It is normal to feel your perineum contracting, just continue to apply the pressure until the contractions cease. It will have the sensation of orgasm, without the ejaculation, so you'll be able to keep going. And you thought that area was worthless.
ADVANCED TIP
Try sitting on a chair with a racquetball (or similar) pressing up against the spot. Have your lover straddle you and she is ready to ride all night long.
Whether you are going solo, or having fun with your partner/s the Mastomatic, is the most relaxing way to cum. No hand movements are required! All you will need to do lie back and let the Mastomatic stroke your love rod.
