The Fashion Police star was fuming when the singer tried to make amends with her mother Sharon Osbourne following her performance on The X Factor UK on Sunday night by presenting her with a birthday cake for Kelly, and immediately took to Twitter to inform Gaga she could "eat my shit".
The Osbournes have been locked in a bitter feud with Gaga for months, with Sharon branding the Applause hitmaker - whose Born This Way Foundation campaigns against bullying - a "publicity-seeking hypocrite" for letting her fans send threatening messages to her daughter Kelly after she criticised Gaga's 2012 Grammy Awards outfit.
It seems X Factor judge Sharon was willing to put the feud behind them as the former enemies hugged it out and posed together with a photo of a birthday cake Gaga had brought for Kelly. They had also met at London's G-A-Y nightclub on Saturday night.
Gaga warned Little Monsters
However, outspoken Kelly - who was watching from the US - was far from impressed and took to Twitter to tell her nemesis what she really thought of her peacemaking skills.
In an increasingly angry series of tweets, she ranted: "Not to be ungrateful but why would you send me a birthday cake via my MOTHER in a country half the would away? #JustSendItToME #LoveNotWar
"#EatMyShit #Hypocrisy / #StefaniStopIt! / You are so far behind you think you are first! / I live for a #Cause not for the #Applause!!!!!!!
"I like desert, but i prefer the truth... it's sweeter / 'Let them eat cake' #MarieAntoinette (sic)".
Not to be ungrateful but why would you send me a birthday cake via my MOTHER in a country half the would away? #JustSendItToME #LoveNotWar
— Kelly Osbourne (@KellyOsbourne) October 27, 2013
I live for a #Cause not for the #Applause!!!!!!!
— Kelly Osbourne (@KellyOsbourne) October 27, 2013
While Gaga didn't respond to Kelly's messages, she warned her fans - who she calls her Little Monsters - to keep their opinions to themselves.
She posted: "Monsters, please just focus on the positive of tonight's performance and do not send any hateful messages. I don't support it. #SpreadLove"
Monsters, please just focus on the positive of tonight's performance and do not send any hateful messages. I don't support it. #SpreadLove
— Lady Gaga (@ladygaga) October 27, 2013
,br>Sharon joined the feud after Kelly was inundated with abuse from Gaga's fans online. The showbiz matriarch also voiced her disdain for the star in her new autobiography, Unbreakable.