Not everyone has that custom.
In my family, for example, we have always fulfilled it, starting on Wednesday and coughing on Fridays until the end of Lent. Since I was a child I thought it was a punishment, but now I see it as a way of respecting in some way what happened to the son of God during those 40 days.
For some it is time to party but for others it is a time of reconciliation with God.