1
general::
Prepare for a joyful occasion or a warm welcome. For example, When Bill comes home from his trip to Korea we're going to kill the fatted calf. This expression alludes to the parable of the prodigal son (Luke 15:11-32), whose father welcomed him by serving the choicest calf after his return. [Early 1600s]
American Heritage Idioms
2
general::
Phrase(s): kill the fatted calf
Fig. to prepare an elaborate banquet (in someone’s honor). (From the biblical story recounting the return of the prodigal son.) • When Bob got back from college, his parents killed the fatted calf and threw a great party. • Sorry this meal isn’t much, John. We didn’t have time to kill the fatted calf.
McGrawhill's American Idioms And Phrasal Verbs