Answer:
The author threw it into the alley because his brother called him a "camouflage".
He picked it up afterwards to drape it inside because he will be needing it when the sky is cold.
Explanation:
From the excerpt, we can see that the author reveals that he flung the jacket into the alley when his brother called him a camouflage. There was something that was spotted which made the brother to call him a camouflage.
The author revealed that when he flung over to the alley, afterwards, he went to pick it up and to drape it on his laps. When the sky became cold, he slipped into it.
