Once I was spying, just for fun, on a classmate at a shopping mall. He (Jack) was meeting his friend (Dirk).
Jack (speaking to himself and holding some bubble gum): I'm not going to buy those. They look nice but they are too costly.
Dirk: Hi Jack!
Jack: I'm going to buy those. They are too nice. Hi Dirk!
Dirk: You wanted to show me these bubble gum, right?
Jack: Many many murders are happening here. So let's stay cool and eat some bubble gum.
Dirk: Yes, you're right.
I went straight to the police and I was right. Dirk was lying dead. He wanted to give Dirk one more chance, since he is his best friend.
How did I know that Jack wanted to murder Dirk?