On Shabbath we are obligated to eat three Se’uddoth (meals), one at night and two during the day. (This is apart from the fourth meal which we eat on Mosaei Shabbath - after Shabbath is over).
Occasionally it may happen that, for reasons out of one's control, one was unable to eat a meal on Friday night (perhaps he had to rush his wife to hospital for a delivery that occurred earlier than was anticipated, and so on). In such a case, we still have to eat the three meals on Shabbath. This is done by eating three meals on the day of Shabbath, instead of two. Each meal (including the make up meal) must be eaten with bread.
Similarly, if one was unable to eat the evening meal on a holiday (Yom Tob), it must be made up during the day. (Two meals are eaten on holidays, unless they fall on Shabbath, in which case it is three).
(See Ben Ish Hai, Shanah Beth, Parashath Wayera, Oth Yod Teth)
See what people are 
