[Slick]

Crystal meth will mess you up, but I don't recommend using it in a story. It actually destroys your brain. CAT scans clearly show holes in a brain after sustained use. It also alters personality, usually permanently after not much use.

As for what will mess up someone's life, here's a real-life example. A male friend of the family is pretty average looking but a great husband who loved his wife dearly. His wife was very beautiful, which made him excessively untrusting of others (and his wife somewhat) because he thought that everyone was after her. To make a long story short, one of his friends, while attempting to make a joke about his suspicious nature, asked him who it was that he saw his wife with the previous day. This ended up in a very nasty divorce and a 3-way hate triangle between the original man, his truly faithful wife, and the joker who repeatedly tried to undo his mistake unsuccessfully. How's that for not getting the expected result?