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^{The "offensive" card Photo: Twitter}

The retailer issued an apology for the comments after being inundated with messages from angry customers.

UK-based charity, Rethink Mental Illness (RMI), said the remarks were "deeply offensive and insensitive".

"It's disappointing that Joy is selling a product that trivialises mental illness in such a flippant way … but its subsequent remarks on Twitter were even worse," said RMI CEO Mark Winstanley.

"Bipolar disorder is a serious mental illness which affects around 1% of the population, and it can be very difficult to live with.

"The last thing people who have the condition need is a company like Joy making fun of it in such an obnoxious and aggressive way.

"There is already so much stigma around mental illness, and comments like this just make things worse."