I was, once, blown away when my girlfriend tried to reach my prostate while we were having sex... She used her finger..
It was awkward because she came without warning but, boy, what a strong orgasm I had... It was almost instantaneous.
It actually made me feel strange until I realise It was all about the prostate...
I now have another girlfriend and sometimes wish she could do it..Prostate massage is awesome. I guess I don't quite know how to explain it to her...