When a handjob is performed on a penetrating organ.

Not to be confused with:

• handjob_while_penetrating - when the penetrator gives a handjob to someone else
• handjob_while_penetrated - when the penetrated character gives a handjob to either the penetrator or another character

Also see:

• collaborative_sex - if the character giving the handjob is not the same one being penetrated
• guided_penetration
• assisted_sex - doesn't necessarily involve direct sexual contact
• masturbating_while_penetrating - when the "handjob" is performed by the penetrator on themself