Dirty Number
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.