Michael Jackson may be remembered as the ‘King of Pop’ … but his pal Lionel Richie remembers him as being one stinky dude — literally nicknamed ‘Smelly’!

The “American Idol” judge talks all about it in his new memoir “Truly,” which debuted Tuesday. He writes the late Quincy Jones is the one who offered up the unique nickname … and MJ didn’t take it too personally as he laughed along, “realizing that he was oblivious to the fact that he hadn’t changed or washed his clothes for a couple of days or so.”

Lionel says it wasn’t the “Thriller” hitmaker’s fault — he was constantly on the road and he couldn’t simply hire a dry cleaner, ’cause they would often steal his clothes as a souvenir! He also couldn’t just drop by a department store for new clothes due to his level of fame, he further reasons.

He further remembers Michael’s attire when they’d hang out, penning … “Whenever Michael came to visit me, he was wearing whatever — jeans and a t-shirt. And the jeans were either falling off him or too short to even be jeans and, well, smelly.”

He adds he helped his pal out one time when he noticed he was “smelling particularly unkempt” and snuck him home so he could shower for the first time in days. He also gave him a clean pair of underwear and jeans.