Not sure about Prostate orgasms. But ASAP orgasms are the bees knees. What's an ASAP orgasm? Glad you asked - Ampulla, Seminal vesicle and Prostate that's what it is.
It is about using all -ahem- resources. The Ampulla holds sperm, the Seminal vesicles hold fluid and the prostate drives ejaculatory reflex (as well as prostatic fluid). Properly stimulating the ensemble leads to a 10-12 contraction wet orgasm as opposed to a 4 contraction for penile orgasms. Also the refractory period is shorter thus multiple wet orgasms are possible. The procedure is used (and taught) in fertility clinics where more elegant methods of sperm collection are favored (as opposed to cattle prod up the ass).
Prior abstinence is not required, albeit it enhances the intensity (same as anticipation).
Cleanliness is paramount (no abrasive/irritating matter) as well as copious lubrication (silicone lube, plenty of it).
Fingers are too short to reach; a proper stimulator (e.g. Njoy wand, but there are better) is necessary.
With an adept partner the first orgasm will occur in a few mins. If you are lucky to have a partner who knows what she's doing, she can draw out the experience to 15-20mins, which puts the receiver in a trance-like state, jacked-up on you own natural feel-good chems. She can also get second one relatively easily after that - the appeal of which is that it's so intense, it's almost painful. After? You'll be wrung out, useless.
The only thing is that one such lover ruins a man for other partners. As mentioned, you will be jacked-up on your own feel-good. And guess what? That's very addictive. To boot, the worship aspect (from your lover) and your surrender being rewarded creates a very strong bond. So guys beware, this garden has thorns.