Genital grasp
A male gently grasps the scrotum or penis of another male. This is an affiliative contact often accompanied with lipsmack or silent bared-teeth displays. Grasping the penis is a frequent occurrence among males in crested macaques where it may be mutual (as in this video).
Thierry, B., EL, B., Baker, S., Matsumura, S., Muroyama, Y., TG O, B., ... & Watanabe, K. (2000). The social repertoire of Sulawesi macaques. Primate Research, 16(3), 203-226.