Triple Negative 

similar to a double negative, but with another negative added in, making a befuddling mixture of words that makes a negative statement.

an excellent way to disagree with someone and walking away while they try to figure out what you just said

Person1: hannah montana is a great singer

Person 2: i cant say i dont disagree with you (walks off)
(^triple negative)

Person1: wait...what?

Triple Negative by Jazz Hammerhands November 6, 2009

Triple Negative 

A way of vocally pointing out that you are not smarter than the average bear.

An example of a triple negative:

Today one of my colleagues said “No-one has not done nothing for me”.

It makes me wonder if I am too intelligent for this job...

Triple Negative by flammable55 October 18, 2017

Triple-negative breast cancer 

TNBC refers to any breast cancer that does not express the genes for the 3 most common breast cancers, namely, Estero gen receptor (ER), progesterone receptor (PR) and HER2/neu. TNBC is more difficult to treat because most hormone therapies target one of the 3 receptors.

Triple-negative here hs a medical meaning. Triple-negative here does not mean an added negative to a double-negative.

Triple-negative breast cancer has a relapse pattern that is different from hormone-positive breast cancers.

Triple-negative breast cancer by Waterbear March 5, 2019

Triple negative rainbow 

depression. the opposite of double rainbow. rather than orgasmic and euphoric amounts of happiness, it is quite the opposite.

Joe: You feeling double rainbow today?
Timmy: No. Actually I'm feeling pretty triple negative rainbow.

Triple negative rainbow by tripledepression(y) December 1, 2010