The pair hit it off and have become good friends, but the "Suicide Squad" actress revealed things got a little messy when she recently hung out with the Emmy Award-winning star, after they were both caught short needing the toilet.
"I was with her last week - I had a reunion with a lot of my English girlfriends and she came along and she’s one person there that no one knew, because she's my newest friend," Cara told Cosmopolitan U.K. magazine, before blushing over the night's unfortunate ending. "I think me and Phoebe peed on the lawn outside of a drive-thru McDonald's."
Explaining how the situation came about, the star added: "It was hysterical - we needed to pee so badly but we were on a party bus and we were like, 'Let's get out at McDonald's.' They wouldn't let us use the toilets so we just peed outside on the lawn outside it."
However, clearly besotted with her new pal, Cara had nothing but good words to say about the "Fleabag" star, gushing: "Phoebe Waller-Bridge could be the Prime Minister. She's one of my really close friends. She's a babe."