Jonah Hill has quipped that he uses a hydrating argan oil mask to stop his hair from turning into Christopher Lloyd's in 'Back to the Future'.

The 'Knocked Up' star has revealed the 10 items he cannot live without, including the nourishing hair mask to keep his locks "silky smooth", which he uses as he's always surfing and bleaching his hair.

The 37-year-old actor joked that if he doesn't use the product, he ends up looking like Doc Brown from the 1985 sci-fi classic.

Sharing his essential items in a video entitled '10 Things Jonah Hill Can't Live Without', ​he told GQ: "Hydrating argan oil mask.

"This is a good cutty move for you guys at home, anyone who like bleaches their hair or f**** with their hair a lot.

"I bleach my hair a lot and I'm in the ocean a lot, so it gets all like Doc Brown, like frizzy,

"you know, like Christopher Lloyd in 'Back to the Future', so, you just throw it in after you surf or take a shower and then you leave it in and you're good to go.

"It smells good and it leaves you feeling

"like silky smooth, you know?"

The director also has a penchant for things that smell good, including Mr. Zog's coconut sex wax.

He added: "This is my next essential item, Mr. Zog's coconut sex wax.

"It's awesome.

"It smells really good. I love the way it smells.

"Green is my favourite colour, so I gravitate towards green things.

"It's pretty iconic and then it's also good and smells good.

"Which is like... I like smell."

And when he's on set, he always has incense burning.

He said: "Another thing is smell.

"Like it really smells bad most places you're shooting, so I really like this incense I like to bring.

"It's called, I don't know how to pronounce the company.

"Astier de Villatte.

"I ain't fancy, so I don't know how to pronounce it, but I know how to smell it.

"It's good."