getting erect flexing PC muscle

[Aimingforthetop]

i keep hearing about people who can get a full erection simply by pumping blood in their penis with the pc muscle.

i have come to the point where i pretty much stop a full blown ejaculation by flexing it. however the ability to pump up my cock is not something i have experienced.

can any of you laborate how to flex it to fill it up with blood?

or any other inside knowledge about this. thanks in advance