How to understand this joke?

There is a widely circulated story: after the Chengdu bus burning incident, a CCTV reporter interviewed an escaped passenger. Q: Is there a hammer in the car? The passengers are from Sichuan. There is a hammer. Q: Since there is a hammer, why not knock on the window? A: A hammer, a hammer. The reporter is puzzled: There are two hammers? The passenger scolded: You said he was a hammer! A reporter at a loss ...

This joke vividly shows the language contradiction between Mandarin and Sichuan dialect, especially Sichuan dialect. In Mandarin, a hammer is a hammer, while in Sichuan dialect, a hammer can be a hammer, or it can be manifested as empty talk, nonsense, bullshit and so on. To put it more bluntly in Sichuan dialect, it means bragging when you have time and lying every day.

Sichuan dialect actually belongs to the northern dialect area in the language system. Many northerners say they can understand Sichuan dialect, but they just want to speak slowly. If Sichuanese say Trump, the burnt Mandarin will not be understood by northerners. However, some words in Sichuan dialect have unique dialect meanings, and northerners can't understand them when they hear them clearly. Such as the hammer mentioned at the beginning.