This exercise is very simple and will kickstart the gains for every hardgainer out there.Your penis will be forced to grow in order to survive.
The Exercise :
Stand up and get in the final position of the Mandingo stretch as described here >>
http://www.mattersofsize.com/forum/showthread.php?55350-The-Mandingo-Stretch-As-Named-By-Blue-Whale
Now simply put the opposite arm(V-shaped) on the extreme base of the penis beneath the arm holding the mandingo stretch = your skin between your thumb and the index finger should be the spot where you are applying downward stretch.
Now at the same time with the right arm apply the regular mandingo stretch and with the opposite arm(forming a V) apply downward stretch at the same time.
Imagine you want to rip your penis appart thats what your intention should be(methaphoricly).
If you do the exercise right you will instantly feel incredible pain inside your penis as a result of the stretching force beeing applyed to your tunica,your bulb and the inside of your penis around the anus and underneath the balls.
Enoy your big penis.
Regards.Blue Whale.