Task: Question Answering
Input (English): Passage: Struggling actor Andrew Largeman wakes up from a dream—in which he apathetically sits on a crashing plane—to a telephone message from his father, telling Andrew that he needs to return home because his mother has died.
Andrew leaves Los Angeles and returns home to New Jersey to attend the funeral. He recognizes the grave-diggers as old friends Mark and Dave, who invite him to a party that night. At home, Andrew's father gets him a doctor's appointment for headaches that he's been having.
Later that night, Andrew goes to the party where he meets up with Mark, Dave, and Jesse, an old friend who has just earned a fortune after creating silent Velcro. After smoking marijuana and taking ecstasy at the party, he still remains detached.
The morning after the party, Andrew proceeds to the appointment. In the waiting room, he meets a young woman named Sam, who is a pathological liar. She later explains that most times she does not know why she lies and will always admit to them afterward. In Andrew's meeting with his doctor, it is revealed that Andrew has been on lithium and other mood stabilizers, as well as antidepressants, since the age of 10, but has recently stopped taking them. He also says that his father, who is his psychiatrist, put him on the medication. Andrew finds Sam outside the office and offers her a ride home. Sam invites him into her house, and he meets her mother, who inadvertently reveals that Sam has epilepsy. Andrew tells Sam of his mother's death, and Sam tearfully eulogizes her hamster. After returning home, Andrew's father confronts him and is insistent that they have a talk before Andrew leaves. 
Question: How does the actor know the grave-diggers?
Output (English): old friends.