Through Dou-sama, everlasting peace & unity...
The gag in pages 12-13 likely references a popular Japanese nursery rhyme, やぎさんゆうびん (Goat Mail), in which a pair of goats (one white and one black) attempt to exchange letters but both have a habit of eating the letters they receive before reading them. Feeling guilty, each then sends the other a reply letter asking what the previous one said before being subsequently consumed by the recipient on accident in an endless loop.