6.9 

6.9 is when a male or female and a female partner are performing the act of 69, where the two are simultaneously performing oral sex on each other, and the female partner begins to have her period. It is called 6.9 because a period ruins the 69.

Last night me and my girlfriend started 69ing, but it turned into a 6.9 and there was blood all over my bed sheets.

6.9 by Phasmid9 March 12, 2017

6.9 

A great thing ruined by a period.

This is a common joke. A 69 is were two people give each other oral sex at the same time. When a woman is on her period this is impossible due to all the blood. This is a joke were 69 is the great thing, and the actual period is making it a 6.9, while it's also true that a woman's period ruins a 69.

Me and my girlfriend were going to do a 69, but it turned into a 6.9
What's that?
A great thing ruined by a period
LMFAO

6.9 by Sheet Smart ;) April 27, 2017

6.9 

a good thing ruiend by a period... DAMN THAT 6.9!

6.9 by §arah April 1, 2003

6.9 

A sex position similar to the sixtynine, but when a girl has her period during the 69. It can occur with lesbians or with straight couples, however gay guys are typically safe from this phenomena of bloody discharge. It is named as such because it is 69 interrupted by a period, hence: six point nine.

Guy 1: Dude, last night this girl and I were 69ing when she had her period on my face! It was nasty!

Guy2: That sucks! I hate 6.9s.

6.9 by Dickalicious April 28, 2009

6:9 

Pronounced "6 outta 9" A sex position similar to the 69, except that each partner defecates into the other's mouth. Common sense would dictate that each dot represents a turd being consumed by one of the partners, but the position is represented as such do to the 6 and 9 being separated by a colon, a clever play on words as well as poignant symbolism.

"Can you believe I have to pay an escort $1200 for a 6:9 these days?"

6:9 by Bearded Justice November 15, 2011

6.9 

The most disgusting oral sex you can have, a 69 ruined by your girl's period

Dude #1: "Did you just eat a cherry popsicle?"
Dude #2: "No, me and my girl were doing the 69, but I had no idea it was her time of the month so it became a 6.9"

6.9 by M24K10 August 27, 2015

6.9 

A wonderful experience ruined by a period

“Man, I went to Susan’s yesterday for some fun but it ended in a 6.9.”

6.9 by TheModernDanielWebster December 29, 2018