It’s a delicious deal that’s been decades in the making.

Jimmy Rush just turned 80, and to celebrate, he bought a few of his closest friends and, most importantly, his 99-year-old father, Jim Rush, to Wintzell’s Oyster House in Mobile, Alabama.

They decided to eat there because of a sign that’s been posted in the restaurant for decades.

“Free oysters to any man 80 years old accompanied by his father,” it reads.

Wintzell’s posted the sign in jest, but as Jimmy edged closer and closer to 80 and his father remained in fine health well into his ninth decade, the sign became more of a goal than a joke.

“The Rush family has been part of this place for years, and they didn’t come alone,” reads a Facebook post by the Oyster House. “A full room of friends, shared memories — and yes, oysters on the house, true to our founder’s promise.”

“Oh, yes!” Jimmy told NBC affiliate WMTV 15, who was present for the free oyster party. “Years! My brother seen it, we’ve talked about it and come down and looked at it many times to make sure. And we asked about it: ‘Is this for real?’ And today, it’s for real!”

That brother, Carl Rush, attended the birthday celebration at Wintzell’s, where his older brother cashed in his free oysters, and says a friend of the family first noticed the sign back in 1972 during a Mardi Gras celebration.

So, the family has waited more than five decades for this mollusk-filled moment.

“We always figured my dad would make it,” Carl tells TODAY.com. “He eats real healthy, doesn’t take any medicine, and he walks four or five miles every day.”

Carl says his family has lived in the area for decades. His dad graduated from the local high school in 1943, his brother, Jimmy, graduated in 1964 and he graduated in 1962.

“We have a sister who graduated in 1973, so we’re all Mobilians and going into Wintzell’s,” Carl says. “My dad, he worked at the post office for 30 years. He served in World War II and Korea.”

The sign says 80-year-olds get free oysters — not just on their birthday — so, technically, this means free oysters for Jimmy’s entire 80th year, as long as he brings his dad with him.

But, Carl says, “We don’t mind paying for the oysters,” with a laugh.

Carl, who will be 78 in October, already has his 80th birthday party location set.

“Two years from this October, we’re going back to Wintzell’s to do this again,” he says. “My dad said he was planning on being there, so he didn’t leave me many options.”