Justin Bieber's Paternity Suit Spoofed By Jimmy Fallon (Video)

Justin Bieber, Jimmy Fallon - Video Still - BLOG ONLY - 2011

Justin Beiber may not be laughing about the claims that he fathered a child last year. 

But, Jimmy Fallon sure is. 

PHOTOS: MTV EMAs Performers 2011: Selena Gomez, Justin Bieber and Lady Gaga

The late-night host spoofed the singer's famous "Baby" song with a new rendition: "(It's Not My) Baby" on his show Wednesday night. 

PHOTOS: Justin Bieber's Moustaches

Fallon's version of the song referenced Maria Yeater's claims that after having sex with Beiber backstage at his Staples Center concert last October, she gave birth to a son, Tristyn Anthony Markhouse, who was born three months ago.

PHOTOS: Justin Bieber's 'Never Say Never' Premiere

Among the lyrics: "You said we did it. And I'm a dad. My lawyer's trippin' cause this looks bad. You only said this, to get my cash. And now Selena Gomez is gonna kick my ass." 

While the slightly-tweaked chorus is now: "It's not my baby, baby, baby, no. I'm tellin' you it's not mine."

Bieber has denied the claims, tweeting "Im going to ignore the rumors...and focus on what is real, an opportunity to help by doing what i love. Judge me on the music! Love yall!"

Watch Fallon's performance as Bieber below.