Danny, 62, tweeted out his joke and instantly drew criticism from fans.
It's not the first time the DJ has got into trouble on the social media site - he was axed from BBC Radio Five Live after he was accused of being racist towards Meghan Markle and her baby, Archie.
He apologised profusely, admitting he was not aware of Meghan's heritage.
Ex-music journalist Danny Tweeted out after Ozzy, 71, revealed his heartbreaking diagnosis: "Not to be unsympathetic to a genuine hero but when Ozzie Osbourne says his "mild Parkinson's" is down to a fall he once had I'm thinking it must have been when he fell into a vat full of cocaine in 72 and didn't get out again for 35 years."
It wasn't long before Danny's 'joke' provoked a furious response from followers.
Not funny, just nasty and ill-informed.
One said: "Not funny, just nasty and ill-informed."
"It's becoming harder and harder to respect you," commented another.
Ozzy and wife Sharon appeared on the Good Morning America programme in the US on Tuesday (21.1.20) to break the news.
Sharon described Ozzy's condition as: "Parkin 2, which is a form of Parkinson's. There are so many different types of Parkinson's."
Ozzy also reassured fans, and said he was 'far from his death bed'.
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