A salesman from Cisco (not the networking company) rang my house bell, and I opened the door.

Pointing at a picture of an alarm, he says in Mandarin, “That alarm...”, and stopped, as if he didn't know how to continue. So, I continued, “That alarm, so what?”. And he goes, “That alarm, whatever you want, will be whatever you want”.

I then closed the door in his face.

It's apparent that he's trying to sell an alarm system, but he's not even trying to do a preliminary introduction of an alarm system. Perhaps he could have said something like, “Hi, I'm so and so, a salesman from Cisco... I'm selling alarms and I would like to ask you if you're interested...”, and I'll go “No, I'm not interested, thank you.” “No problem, sorry for bothering you, etc...”