Food.
Massive quantities of food.
You see, all Jewish holidays and the Sabbath have accompanying food rituals. There are various commandments (mitzvos) that go along with each day on what you are supposed to eat.
Therefore, when the Jewish holidays fall back to back with the Sabbath, you can have 3 days in a row, followed by another 3 days in a row (five days later) where you eat at least two elaborate meals a day.
Imagine Thanksgiving dinner in the late morning, early afternoon.
Then another one in the evening.
Then again the next day and the next day....
Oy.
However, that is just about the worst thing I can think of about Judaism - this should be the worst problem I ever have to deal with...