Two guy perform 69 on each other while ever so slightly brushing the bottom of the partners sack with their tongue. Depending on the GICL level you can throw in a few tugs for good measure.

An aggressive form of sack play. The tickler stuffs a tickling device in their own anus, while the ticklee lays on their back with his legs spread - sometimes holding their ankles/toes to ensure maximum access. The tickler then squats over them and bounces up and down/side to side brushing the tickling device across the ticklee's (likely small) nutsack; similar to a tea bag motion. The two should be facing each other and staring deeply into one another's soul.

A BICL is when this is done with the tickler facing the opposite direction - a "bad idea" because he won't know if/when the ticklee is thinking about jamming the tickling device further up their ass.