“Ordered a McDouble and won the McDonald’s lottery,” this person eagerly proclaimed. They were blessed with three patties instead of the signature two (hence “McDouble”). Look at that cheesy, meaty goodness! This person hath been bountifully blessed by the fast-food deities that reside in the heavens above.
They essentially received a free patty. Perhaps the employees there took a shining to this customer. Maybe someone harbors a wee crush on them. Thus, the extra meat. It’s a metaphor that we won’t delve into for reasons. But you’re picking up what we’re putting down. We think?