"We were speechless, we nodded," Gage said. "We weren't expecting it."
Stunned, they kept their conversation with the server to a minimum for the rest of the meal, and tipped him 15 per cent - they usually tip 20 - and left the restaurant without addressing it with a manager.
"I'm kind of embarrassed to say we didn't say anything," McKinnon said. "It just took us back to such a shameful place, in a way."
But after they had slept on it, they were angry about the encounter and posted about it on Facebook and Yelp.
When contacted by the Washington Post, the Prime Rib's general manager, James MacLeod, said he was still trying to piece together the situation and hadn't had a chance to speak to the server in depth yet.
"The waiter in question is Bulgarian, and he does speak four different languages," said MacLeod, noting that English is not the server's first language. "I am not sure if he got confused as to what he was saying, or how he was saying it."
He said he planned to contact Gage and McKinnon.
"I cannot believe that a waiter would have ever said anything like that," MacLeod said. "There's no way we would condone anything remotely like this."
Other restaurants - even in liberal Washington - have been publicly shamed for slinging homophobic and transphobic remarks, often directed at LGBTQ patrons who show affection in public.
In London in 2014, a lesbian couple was asked to stop kissing because they were in a "family restaurant". When a gay couple gave each other a peck on the lips before entering an Ohio pizzeria, they were accosted by a staff member, who told them, "You better get used to this, this is Trump's America." (He was later fired.) A gay couple reported that they were asked to leave a Dublin restaurant for holding hands.
Incidents like these make LGBTQ couples believe, as Eleanor Margolis wrote in the New Republic, that they should put the "kibosh on sexuality until after dessert. . . . Same-sex couples are still forced to be careful about where they choose to kiss or even hold hands."
Even if the restaurant tries to make amends, Gage and McKinnon don't think they'll be back.
"It was so humiliating," McKinnon said. "It was unbelievable how it made us feel."