This may not be a very sympathetic or feeling way to describe somebody's death, but it is an eloquent one when brought into relation with an old Catholic custom.
After death, when the body had been laid out, a cross and two lighted candles were placed near it, and in addition to these the holy-water bucket was brought from the church and put at the feet of the corpse. When friends came to pray for the deceased, before leaving the room they would sprinkle the body with holy-water. So intimately therefore was the bucket associated with the feet of deceased persons, that it is easy to see how such a saying as “kicking the bucket " came about.
Many other explanations of this saying have been given by persons who are unacquainted with Catholic custom.