It's rude to take something meant for someone else.
Allen is looking for his headphones in a lost and found bin that is full of clothing that belongs to other people.
Allen wants to add some new button up shirts to his closet.
Allen leaves everything in the bin and stops by the discount store later to grab some new shirts.
Allen takes a nice shirt from the lost and found bin that belongs to someone else.
The person who the shirt belongs to stops by and finds their shirt and is glad they don't need to buy a new one.
The person who the shirt belongs to comes by later and is sad that they can't find their shirt.