Complete the GO Bank job on the Death Wish difficulty or above. Complete the Jewelry Store job on the Death Wish difficulty or above. Complete the Firestarter job on the Death Wish difficulty or above. Complete the Rats job on the Death Wish difficulty or above.
Infamous (Card Drops) These masks are card drops. Each card drop has a 5% chance to include infamous items in its loot pool. The chance of getting a mask ranges from 9.8% at level 1 to 15% at level 90+.
It has been officially confirmed that Jacket and the other crossover characters are canon.
Alienware. Players without an Alienware computer can still access these masks by creating an empty file called lightfx. dll in the root folder of the game and checking the Alienware LightFX box in the advanced video settings.
Holdout becomes accessible at Reputation 65, and players with at least one rank of Infamy can access it regardless of level.
These masks are acquired by reaching certain waves in Holdout missions. They can't drop during a payday and can't be sold. Instead, they can be returned to your mask stash for free, but any pattern, color or material as well as the customization fee to put these together will be lost.
To get a mask you need to open some safes first so get cracking. You can also play the Nightmare Safehouse during a limited time as well. Go into the nightmare version of the old safehouse and relive the horror. The Safehouse Nightmare comes with 4 juvenile masks to collect, distributed over the first 4 difficulties.
Jump! Finish a heist without it ever going more than 4 seconds between you jumping. Unlocks the "Dawg" mask.
Jacket is the first heister who doesn't speak, but rather communicates through "an 80s model dictaphone". Jacket uses a tape recorder which plays all manner of phrases taken out of their intended context, most often language tapes, physical fitness tutorials, fun facts, airplane PAs, and automated voicemail systems.
It is possible that Jacket's real first name is "Richard", since it is the name of the first mask received in the game (mailed to him personally by 50 Blessings), and it grants no special abilities.
From what I can tell based on a little experimentation, Facebook's formula can be explained more simply: When you recommend a business, Facebook assigns your review five stars. When you don't recommend a business, Facebook assigns your review one star.
A relation R on A is a subset of A×A, or equivalently, R is a member of the power set of A×A. For a set S of size n, the set S×S has size n2, and the power set of S×S has 2n2 elements.