Top Definition
Excessively masturbating until the upcoming event of a raw and bleeding penis. RubTub; being the fun part of the event, and Machuggin; the perseverance to get to that point. This is the step Men achieve past Extreme levels of masturbating to reach a common and difficult nut.

Scientists say that RubTub Machuggin' is extremely unhealthy for anyone to accomplish. Studies show that too much RubTub Machuggin' can lead to a leathery foreskin.

We do not insist on anyone subjecting to RubTub Machiggin'; perform this only if you are an experienced RubTub Machuggin' licensed Machugger.
"Oh my God! Your foreskin feels like leather!" - Jane
"Yeah, I used to be really heavy into RubTub Machuggin'."-John
by JugsNRugs March 18, 2011

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