AceShowbiz - Cardi B left U.S. talk show host Jimmy Fallon lost for words after explaining the unexpected meaning behind a line in her new single "Up".

The "WAP" hitmaker is known for her raunchy lyrics, but she caught comedian Fallon off-guard on Thursday (11Feb21) as she revealed one part of the song originally referred to an uncomfortable constipation situation.

The line in question, which she had actually borrowed from her husband, Migos rapper Offset, is, "If it's up, then it's stuck."

During "The Tonight Show Starring Jimmy Fallon" interview, Cardi admitted she initially thought it was a "Georgia thing" as Offset, who is from the state, says it "a lot," but she soon learned fans from other Southern U.S. states are also familiar with the phrase, so she was inspired to use it too.

"Um, so have you ever taken a poop, right, and it don't come out?" Cardi began to explain as the stunned funnyman looked down at his desk. "It's just up and it's stuck. Yeah (sic)."

After an awkward silence, Fallon uttered, "Wow," while Cardi simply nodded.

"I mean, I guess you can take from it whatever you want. There's other ways to look at it, I guess," Fallon reasoned, as Cardi agreed, "It's a metaphorical quote."

The release of "Up" which she claimed was inspired by the Chicago Drill music scene was marred by plagiarism accusations.

The femcee was accused of ripping off New Jersey rap duo Mir Fontane and Mir Pesos over similarities between the hooks on her song and theirs.

She, however, vehemently denied the allegations.