I will tell you what would happen to you if you opened Pandora's Box in Big Brother US.
RasGrand - You will open the box at the top 6. You get to go to the jury house and have lunch with the 3 jurors, but the video of your meal/conversation is played live in the living room for the other houseguests to see.
Austin - You open the box at the top 10, and the 4 previously evicted houseguests are in the box with you. The 5 of you compete in an endurance challenge and if someone other than you wins, they get to re-enter the game. Unfortunately for you, the second person evicted wins and comes back into the game.
Utsumi - You open the box at the top 8. You release a loved one into the HoH bedroom for the next 8 hours. However, while you guys are having fun upstairs, the other houseguests have to stay in the pool for the whole 8 hours or else they will be a Have-Not for the rest of their time in the house.
TheSexiestDude990 - You open the box at the top 7 and release a double eviction week on the house. Come Thursday, someone will be sent packing in 7th place and then you will play a fast forward week and someone will leave in 6th place as well. You are the only person who knows ahead of time, but you can share the information with anyone you choose.