Sean Penn doesn't care about his haters.

The 57-year-old actor released his debut satirical novel, 'Bob Honey Who Just Do Stuff', earlier this week, and has received some backlash from critics who slammed the titular character's decision to kill old people in order to help save the Ozone layer.

But Sean has admitted he doesn't worry about what critics say, as he's had a successful career and no amount of hate will change that.

Speaking during an appearance on 'Conan' on Thursday (29.03.18), the actor explained: ''You know, there's a fashion today of questioning all humour. Or in fact, a sort of self censorship. And what I would say to anybody who is offended by this - because I took care to write a book that starts on page one and doesn't end until it ends - and if read fully in context, what I would say is 'I'm 57, my pool's heated - you can say anything you like'.''

The 'Mystic River' actor's decision to release a book comes after he revealed earlier this month that he no longer has a passion for acting.

He said: ''I think that this has been true for some time.

''It can be great when you're working with good actors or good directors or good writing as an exercise, but do I have a belief that it has a lasting value? Maybe, I could make the argument intellectually.

''But I don't have a visceral ... I'm not in love with that anymore.''

Sean's novel tells the story of a septic tank salesman-turned-assassin who murders people with a mallet, and the star has admitted he knows some people won't understand the meaning behind the book.

He said: ''You know, some people are going to get this book and some people are not going to get this book.

''Some people, I think, will really enjoy it, others will loathe it. And that really is what I'd like to say about me, you know?''