Jamieson, Fausset and Brown on Genesis 43:34

34. took and sent messes ... Benjamin's mess was five times--In Egypt, as in other Oriental countries, there were, and are, two modes of paying attention to a guest whom the host wishes to honor--either by giving a choice piece from his own hand, or ordering it to be taken to the stranger. The degree of respect shown consists in the quantity, and while the ordinary rule of distinction is a double mess, it must have appeared a very distinguished mark of favor bestowed on Benjamin to have no less than five times any of his brethren.

they drank, and were merry with him--Hebrew, "drank freely" (same as So 5:1; Joh 2:10). In all these cases the idea of intemperance is excluded. The painful anxieties and cares of Joseph's brethren were dispelled, and they were at ease.