Unsurprisingly, 72-year-old Meryl Streep did not know what the slang term G.O.A.T. meant
Don't worry, her younger Don't Look Up co-stars, Jennifer Lawrence and Jonah Hill, explained it

There’s no doubt that Meryl Streep is one of the greatest living actors, with her long career of stellar performances and stack of awards to back it up. However, in all of her greatness, it’s only natural that she would not know the slang term used to label those considered the “Greatest Of All Time” a.k.a. G.O.A.T., stemming from the sports community and only popularized online in the last few years.
However, her younger co-stars on the set of Adam McKay’s Don’t Look Up did not think to bridge this generational gap while calling her the G.O.A.T. on set numerous times. In an interview with Stephen Colbert, Jennifer Lawrence explains that Streep genuinely thought her co-stars were regularly calling her a goat, referring to the barn animal.
“We offhandedly call Meryl the G.O.A.T.,” Lawrence tells Colbert. “And we were doing a photoshoot and I said something like G.O.A.T. and Meryl kind of said, ‘That’s right. Just tell the old goat where to go.’ I was like, ‘Meryl, you know that G.O.A.T. means greatest of all time, right?’ And she was like, ‘Oh, no!’”
She adds, “I was like, ‘We haven’t just been calling you goat this whole time.’”