Orlando Bloom finds it ''very hard to impress'' his seven-year-old son.

The 'Pirates of the Caribbean' star has revealed Flynn - who he has with his ex-wife Miranda Kerr - is one of his biggest critics and is difficult to please.

He said: ''He definitely won't be seeing 'Killer Joe' but he has seen some of 'Pirates of the Caribbean'. It's very hard to impress him but he liked it.''

And the 41-year-old actor - who is currently dating Katy Perry - loves the ''massive adrenalin rush'' he has got from starring in a play.

Speaking on The Graham Norton Show, he added: ''It's fantastic and although it's 17 years old, it feels very current. Most people would not think of me in this role after 'Will Turner' and 'Legolas'. It has sensitive material and is quite dark, shocking and challenging. The appeal of the theatre is the response from the audience. It's like free-falling and a massive adrenalin rush.''

Meanwhile, Orlando previously confessed he will be studying animals at the zoo to prepare for his gritty return to the West End in black comic thriller 'Killer Joe'.

Speaking about how he'll work on the part of detective Joe Cooper - who has a side job as a contract killer - he shared: ''This play is particularly interesting at this time. It's about the disenfranchised American dream. But it's funky and provocative and visceral. It's everything I go to the theatre for ... I will start to look at animals - I'll go to the zoo. I like to find an animal, some kind of creature that helps me to inhabit the character - their rhythm, beat and pace. I'm quite physical as a person.''

The Graham Norton Show airs on BBC One on Friday (April 27) at 10.35pm.