Smith was outside the Red O restaurant in L.A. this weekend, when she explained, "[Michael] was not allowed to sing on the show, so he literally hand-picked a guy to sing like him."
During the famous episode, "Stark Raving Dad," Michael provided the voice to a mental patient who thought he was MJ ... but according to reports, Jackson's record label blocked MJ from singing the Lisa birthday song.
MJ ultimately selected a man named Kipp Lennon -- and Yeardley explains, "How unnerving would it be to sing like Michael Jackson in front of Michael Jackson?"
We called Kipp to find out -- so far, no response. 
