The All Day rapper claims both that Kim Kardashian West approved the song AND that it was Taylor's own idea!
He took to Twitter to share:
[Image via To/FayesVision/WENN.]
And then she saw it. And then she was infected with the Bieber Fever!
Check out the video above of Evan telling the story to Jimmy Fallon — and then totally killing her own rendition of the Bieb's Baby!
Such a fun interview!