Okay, here's another idea that I imagined with charachters from Evangelion, but could also work with other charachters.

=-Death Game==
Basically it's a game where everyone writes down a method of death on a piece of paper (something they would enjoy to see another participant to do, so preferably something painful and entertaining; can be anything from hanging and seppuku to whatever your imagination can come up with), then each piece of paper is put into a separate envelope, then you write your name on it. Then you put the envelopes with the named side down (another option is to put each envelope in another envelope) and mix them all up. Then each participant takes an envelop, checks the name on it, if its their own, they try another one. If its not, they do what is written there to the others' amusement.
The idea for the Evangelion charachters was for Shinji to be the last participant, so after everyone else has killed themselves one way or another (preferably Rei took Shinji's envelope and it was something quite painful and she did it without hesitation for his entertainment; he is in love with Rei, so is having extra fun watching her die in a painful way he designed), he takes the last envelope and it's Rei's. He opens it and finds out the method of death written on it: death of old age. He wonders if she didn't completely understand the point of the game when writing this, but oh well, it was still a lot of fun. The attitude to death is casual enough for him to lament how remaining alive means he now has to clean up all the mess remained of the other participant, but he decides the best he can do to repay for the fun he had watchign others, and especually Rei, die is try to follow what's written and live a long life until he dies of old age.