An unofficial honorgiven for excellence in any field. 'Two thumbs up' is/are not contained to any profession/achievement, and, therefore, can be awarded for any outstanding accomplishment.
When Ebert & Rober give a movie two thumbs up, does each of them contribute one thumb?
A sexual activity between three people, including at least two women, in which the third person is lying down on his back between two women who are kneeling up and supporting each other, while the person lying down uses his thumbs to massage the insides of the women's vaginal walls, thus causing both his thumbs to be in the upright position.
"Suzie, Betty, and I had a great time last night. I gave them two thumbs up while they were making out."
When you have to pee in a movie but don’t want to miss anything, and must do the following mental equation: will the amount I have to pee cause enough discomfort to diminish my attention capacity for the remainder of the movie to an extent which is greater than the amount of the movie I would miss by making a mad dash to the restroom.
I saw Satantango last night, wonderful film but by the 5th hour I had to start doing pee calculus.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).