The co-hosts called back to a scripted segment during the opening of the 2014 CMAs in which Paisely "accidentally" revealed the gender of Underwood's first son with husband and former NHL player Mike Fisher, as Paisely goaded her to announce the gender of her second born.
"That doesn't even make sense!" Underwood responded.
She ultimately gave in to Paisley's teasing and exclaimed "Willie, it's a Willie!" indicating the couple were expecting a second son.
Paisely went on to say having two sons can be difficult and claimed to bring out Underwood's firstborn son for a special presentation.
Instead viral "Walmart kid" Mason Ramsey took the stage, as he and Paisely sang about the "big brother blues."
The opening monologue also featured a song poking fun at Bradley Cooper and Lady Gaga's adaptation of A Star is Born and the awards show itself for being a boring affair that lasts three hours but "can feel like four."
Underwood and Paisely also poked fun at a viral proposal during Emmy awards, joking one of the nights winners would get a divorce.
Paisely then performed a song pitching Underwood on the idea of a "bar and day care center," stating it was "completely irresponsible to get drunk at home with your kids there."
They joked the day care would be located among other fictional Country music businesses including "Jason Aldean's Kitchen and Rooftop Bar."
The pair also riffed on the viral dance craze "flossing" as Paisely wondered aloud, "Well, how is that supposed to prevent gingivitis?"
Before tossing to the first group of presenters, Paisely said 2018 had been a big year for men in country music, to which Underwood responded, "Yeah! Finally!" to laughter from the crowd.
"There are so many dudes in Country right now it's hard to keep them all straight," Underwood said.
Paisley quickly corrected, "well they're not all straight, just George," referencing the "King of Country" George Strait.
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Moments from the CMA Awards red carpet