The rule of thumb for sexual intercourse , esp. in male homosexual activity , in regards to the size of the giving participants penis.
Whenever the penis is larger then 6 inches, then the receiving participants only agree to receive 1/3 of the phallus of the giving participant.

This rule dose not always apply , as some male homosexual intercourse goes by the 'breath through the pain' rule, and clarification is expected to be communicated prior to the encounter over the interwebz or in eye contact in the nanoseconds before the door closes and penetration occurs .
Kevin Smith was interviewing Malcrom Ingram, as Malcom admitted his dismay upon the idea of accepting a full nine inches of raging man meat. Kevin reminisces of his mothers 'frugality' , gets lost in a haze of 'foggy' memory, then returns to introduce to the SModcast community and the entirety of the internet the 1/3 rule.
Kev, this is for you good sir.

tarinbutler3002@yahoo.com
by eat cock-Oh we totally DO October 15, 2010
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When using public bathroom, using urinals, 1, 3 and 5. No 2 and 4 just in case others come in. Never be next to another man using a urinal. Also no talking why using the bathroom.
WTF, your in 2!!
So...
1, 3, 5 rule!!!
by Urban Dictionary January 18, 2008
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The rule that when out drinking you can easily drink 3 pints before you need your first piss but thereafter it's one pint, one piss for the rest of the evening.

(Also applies to drinking tea if you're British).
"I've gotta go piss dude, the 3-1-1 rule's just kicked in".
by Woody72 May 22, 2017
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