Live exercise: Why are all the police tied up?

Su Yu traveled through a parallel world and became a sixth-grade student. At the beginning, he was selected to be the subject of safety education.
I originally thought it was just a simple science popularization for children.
Unexpectedly, after the prank system was triggered, the style of the painting gradually began to deviate.
When the police pretended to be couriers and went to the door to conduct tests.
"Hello, courier, can I come in and have a glass of water?"
"no problem."
Policeman: "Have you ever thought that I am a bad person?"
Su Yu: "Oh, have you ever thought that this glass of water was scooped from the toilet?"
"puff!"
Police: “Aren’t you afraid?”
Su Yu: "I was afraid at first, but not now."
"why?"
"Because it was drugged!"