For Ricky Gervais, making people laugh is part of his job description, but instead of having the disabled community guffawing, the comedian's latest round of Tweets has left them outraged.

The Office creator posted a series of tweets including phrases such as Good monging everyone and two mongs don't make a right, which are not complete without the pictures of him making silly faces to accompany them.

But disability rights groups are not laughing.

Nicky Clark, a People Not Punchlines campaigner whose daughters both have disabilities, said Gervais is encouraging bullying with his choice of words, The Daily Mail reported.

If you use a word relating to disability as an epithet for something stupid or foolish, then you are compounding the problem.  This isn't irony and it's not his word to reclaim, Clark said. His fan base is now using the word to attack me and others who have criticized him on Twitter. A new generation who didn't even know this word is using it abusively, and that's bullying.

Urban Dictionary defines mong as short for mongoloid, which, in its original anachronistic term is used to describe a person with Down's Syndrome. Gervais, however, criticized the humourless PC brigade on his Twitter account, saying the term mong is now commonly used to refer to someone who is very stupid.

The modern use of the word mong means 'dopey' or 'ignorant,' Gervais said in a statement. It's even in modern slang and urban dictionaries.

On Sunday, Gervais released a statement, saying:

I have never used the word Mongol. I have used the word mong. But I have never used that word to mean Down's Syndrome and never would. I have explained, even during stand-up shows, that the meaning of words change over time. Gay, for example, would never be used to mean happy any more. The modern use of the word mong means Dopey or ignorant. It's even in modern slang and urban dictionaries.

Comedian Richard Herring compared Gervais' use of the word to racist or homophobic slurs, saying that comedians would never are to use such language when talking about race or sex.

I think many comics are guilty of using [slurs against disabled people] as convenient and humourless punchlines, Herring wrote on his blog. I think they do equate with those racial and homophoic epithets that are rarely heard these days. They do confirm the stereotype of disabled people and contribute to their further isolation in a world that already tires to pretend they don't exist.