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1.
An elaborate, ceremonious salutation between close male friends. When two friends who haven't seen each other in a long time are reunited, they immediately drop trow revealing their sacks, then hold them in an outward-facing position and run directly at each other. This is typically executed at full speed and in perfect alignment. The result is that both participants dangerously collide sack-first, causing them to repel off of each other in a cartoon-like, elastic fashion, ultimately sending each friend into random, disoriented trajectories where hazards likely await.

The sack bump is a kin to the well-known chest bump and fist bump. However, the sack bump is a superior and more valued greeting ritual, reserved for parties who hold the utmost respect for one another.
The epic sack bump of '89 sent Gordon off a balcony, shattering both his legs and his penis, while long-time friend Herbert was hurled under a taxi cab, bursting his coin purse apart instantly on impact.
by JDirty September 27, 2013