Mainly used by those who are uncircumcised, it is the placing of one penis under the foreskin of another.
Circumcised males can partake in this act, by use of a special device known as a 'docking sleeve'.
To place the head of one penis, so it is under the foreskin of the other, while having that person's cock head placed under their own foreskin.
Then to rub them together, to heighten the sexual pleasure, stimulation.
Use of a special device, known as a 'docking sleeve' can provide similar experiences for those who are circumcised.
It is a form of foreplay, and generally is done prior to more intense sexual acts. As well, it can be done, while also engaging in other more standard foreplay, such as kissing, touching, caressing.
It is usually done in the standing position.
Noteworthy: A Docking Sleeve is generally made of a pliable material, including cyber skin.
It is open at both ends, allowing the two participants to insert their penises in one end, to meet within the tube structure, and to then move in such a fashion, as to cause the two penis heads to rub together.