Noun, sense 1. An affectionate synonym for 'vagina'. See also gash.
Noun, sense 2. Someone with whom you basically just get drunk and/or high and have sex, usually on a short term basis. Compare to "your girl" or "a ho", both are higher on the intimacy ladder.
Sense 1: "I am so going to hit that notch, bro."
Sense 2: "Are you going to the prom with him?" "Naw. He's just a notch."
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