The Couple were a pair of people who Boybrush Threepwood and Chuckie pretended were their parents while playing, perhaps due to their likeness to Guybrush Threepwood's Parents.
They did not appreciate being part of the children's game and wished to be left alone. They generally seemed to dislike children, considering them to have no respect for their elders.
They had brought bread with them to the park so that they could feed ducks, and were not keen to share it.