Colbert opened the show directly addressing the President's Irish snafu, calling the commander-in-chief's remarks "very nice" and "very sweet."
"Trump's favorite Irish proverb is not a proverb; it's a poem," Colbert said. "It's not from Ireland. It's written by a Nigerian poet named -- wait for it! -- Albashir Alhassan."
The late-night host proceeds to read from a fictional book penned by the President titled "Bigly Irish Sayings," to include "You better call Becky with the good hair," which Colbert refers to as "Black Irish."
See more funny gems of Irish wisdom courtesy of the President's spoof book in the video above.
For his part, Fallon creatively reimagined how various members of the Trump administration celebrated Friday's Irish festivities.
"President Trump is a big fan of the Irish which is why yesterday he sported the colors of their flag," Fallon opened the show. "There he is with the green tie, white shirt, orange skin," the comedian said, referencing a photo of Trump on St. Patrick's Day alongside a picture of the Irish flag.
In the monologue, Fallon suggested that Kellyanne Conway's holiday celebration involved a microwave, and AG Jeff Sessions' "celebration" didn't even require a costume.
See Fallon's good-humored digs in the video below and then watch the original President Trump moment below.