Top definition
A number that indicates how dirty you are.

"A quantitative measurement of one's promiscuity"

The intention being mainly bragging, but also a sex-positive attitude that appreciates sex rather than regarding it something bad - for both men and women.

The calculation goes:
Dirty Number = X * (A1+A2)
Where

X is the number of partners you have slept with
A1 is the highest age difference you ever had to a partner younger than you
A2 is the highest age difference you ever had to a partner older than you
Dude, my dirty number increased to 213 last weekend.

I have slept with 18 women, once with a woman 7 years younger than me, once with a woman 5 years older than me. My dirty number is 18 * 12 = 213.
by F64 December 10, 2011
Get a Dirty Number mug for your cousin Rihanna.
2
A quantitative measurement of one's promiscuity to allow for easy comparison, bragging, etc. It is calculated by multiplying the number of sexual partners with the combined age difference. The combined age difference is calculated by adding the age difference to the most younger partner with the age difference of the most older partner.

If I have slept with 5 people, and the age difference to the most younger one is 2 years + the age difference to the most older one was 3 years, then my dirty number is

5*(2+3) = 5*5 = 30
My dirty number is 148, what's yours?.
by F64 December 08, 2011
Get a dirty number mug for your sister-in-law Nathalie.