Why does Norton call Lorraine a "screech owl" in chapter 9 of Paul Zindel's The Pigman?

A screech owl is known for its high-pitched, loud, and annoying call. Norton probably calls Lorraine a screech owl because of these well-known qualities. However, Norton's derogatory term is unfounded because Lorraine doesn't go around screaming like a screech owl. Norton most likely uses the term because he is jealous that Lorraine has been monopolizing John's time recently. A screech owl would certainly claim someone's attention in the wild if a person heard it screeching. Similarly, Norton may feel that Lorraine has caught too much of John's attention.
Norton also knows that John and Lorraine have been spending time at Mr. Pignati's house, which makes him wonder why two teenagers would hang out with an old man. Norton's interest in the old man is to steal from his home, though, as shown in the following passage:

"'Has he got anything worth stealing?' Norton clarified, his eyes beginning to get mean and sneaky like an alley cat about to jump on a bird" (100-101).

When John won't tell Norton about the possible loot he could steal from Mr. Pignati's house, Norton attacks Lorraine in an effort to discredit John's association with her.

"Norton had reached a new peak of ugliness that day with the afternoon sun shining down on him. He paused a minute, then took a sip of his beer. 'Well, what are you and that screech owl going over there for?'" (101).

If Norton can make John feel ashamed for hanging out with Lorraine, then he thinks John will help him steal some valuable items from Mr. Pignati's house. Remember, Norton only calls Lorraine a screech owl after John refuses to provide information about Mr. Pignati's property; therefore, Norton calls Lorraine a screech owl because he is mad John won't help him steal from Mr. Pignati.