A: I forgot my house key!
B: How are we supposed to get into the house?
A: I hid a spare key in case this happens.
B: Let me guess: it's under the mat?
A: How did you know?
B: It's the most obvious hiding place.
A: I didn't know where else to put it.
B: There's a lock that allows you to hide keys in it.
A: Wow, really? That sounds like a good invention.
B: My teacher has one for his room key.
A: Of course, the best solution would be not to forget the key.
B: Definitely. Be more careful next time!