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A phenomena occurring during gay sex where the giving man's scrotum slaps the receiving man's scrotum, sending them forward to the grundle then back to hitting the giver's scrotum, which then swing backwards, and repeats.

This is derived from the desktop toy known as Newton's balls
Hannable was riding Adam so hard that the Newton's Grundle could be heard from outside the bathroom.
by horribleperson24601 April 15, 2014
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Jun 14 Word of the Day
Referring to women who are sexually or romantically attracted to other women. Applies to both lesbians and bisexual women, as it is only the same-sex attraction that matters, not any other attractions the women may have.

Originates from the Greek poet Sappho, a bisexual woman from the Isle of Lesbos, from which we get the term lesbian.
The sapphic women greatly enjoyed each others company.
by whatisdead June 25, 2015
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