You shouldn't allow sick people at your birthday party.
Rocky is hosting a group of friends for a birthday dinner party at his house when his friend Steve shows up and is clearly sick.
Rocky wants to respond to Steve's arrival.
Rocky convinces Steve that he shouldn't be around a group of people and should go home and rest.
Rocky invites Steve in to join the rest of his guests at dinner.
The guests have a great time at the dinner party, and no one else gets sick.
The guests are all exposed to Steve's illness, and everyone gets sick a few days later.