The deep, dark depression one sinks into upon finishing the fifth Harry Potter book. The mood is characterized by a feeling of intense loss, loneliness, and hopelessness. Essentially, there is a deep black chasm somewhere near the heart.
Concerned Friend: What's wrong with Ted? Has he been crying?!
Wise Friend: He's fell into Sirius Blackness. I'll give him some chocolate.
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).