An artist who launched his own clothing range during the coronavirus lockdown is facing a legal battle with fashion giants Hugo Boss over his merchandise.
John Charles, from Huyton, Merseyside, would end his lockdown online art lessons by saying "Be boss, be kind".
His sign-off was so popular it led to a demand for merchandise with the motto, which caught the attention of the German fashion brand.
A Hugo Boss spokesman said it is "open to a mutual agreement".
"I'm totally shocked to be honest," Mr Charles said. "I'm just one guy in Merseyside I'm no threat to an international business.
"I've got a different logo, theirs is in caps [capital letters].
"When you say the word 'boss' in Liverpool everyone knows what you mean [slang for great] and you are not talking about clothes."
More than 27,000 people logged into Mr Charles' free online classes which he devised with his 10-year-old daughter.
"We always wanted to finish positively which is why we said 'Be boss, be kind'," he said.
"We got people from Australia, Italy and Mexico taking part and their kids are all saying it. I even had people telling me their kids are saying it all round London."
The artist began marketing the slogan after people started asking for baseball caps, T-shirts and hoodies.
"I'm a professional artist - any money is being put into a trust fund for my daughter as she wants to study fashion when she is older - she is pretty gobsmacked that the company have done this," Mr Charles said.
He received a letter from lawyers on behalf of Hugo Boss after he applied to trade mark "Be Boss, Be Kind" in July.
The letter of 22 September said the company wants to block his application but would drop the action if he withdrew it and stopped selling items with the word 'Boss'.
In response to an approach by the BBC, a spokesman for Hugo Boss said: "We appreciate the family's engagement in the currently difficult times and are open for a mutual agreement here. We will be in touch with them directly."