Multiple orgasm is different thing than serial orgasms, or a sequence of orgasms as some seem to be suggesting, it's more like one continuous orgasm, there are peaks and valley's, instead of one big spasm.
The first time I had one, I finally understood this song.
I read the link, and I have to caution against suppressing ejaculation: a retrograde ejaculation can damage the prostate and lead to long term problems, be skeptical of Tantric claims to the contrary, there is no "divine essence" you will exhaust, mainly Zinc depletion if you really do it a lot, which a Zinc supplement will readily fix.
I've found that prolonging it however, shortens my refractory period considerably - not quite what I was at Nineteen, but not bad for an old man.