A situation where a brother and sister are engaged in a session of 69. At some point (sometimes unintentionally) both parties braces become entangled in the other party's pubic hair, leaving each member no choice but to forcefully detach each member's pubic hair while still entangled in their braces. hence; the name lawn mower. (see:Cincinnati Wool Teeth)

Named after Cincinnati, the location of the first documented case.

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