I heard a short programme on Radio 4 earlier, in which Hardeep Singh Kohli was looking at various facts and trivia about mattresses. He asked lexicographer Susie Dent where the phrase "he's thinking of going to the mattresses", uttered in the film The Godfather, came from. Susie said the phrase means 'to go to war with a rival clan'. She explained that mattresses feature a lot in Italian folklore; in the 16th century, during times of war, people were said to hang mattresses down the sides of towers in order to minimise damage from cannon fire.
You can listen to the short programme for another week here. This particular discussion occurred right at the end -- about 13 minutes from the beginning.