How does the author use foreshadowing in The Birthday Party?

In his teasing of Meg, Stanley claims that the two strangers who plan to show up at the boarding house will come in a van carrying a wheelbarrow, which they use to cart somebody off. Meg, a gullible target for Stanley, grows very nervous, fearful that she will be their victim.

Although Stanley's purpose is to frighten Meg, his description foreshadows his own fate. He is the one to be taken off. His teasing story predicts the sinister arrival of Goldberg and McCann and is an important bit of foreshadowing.