Paris Hilton and Nicole Richie "haven't changed" since 'The Simple Life'

Lionel, 74, told 'Entertainment Tonight': "They haven't changed.

"Let me tell you something, those two scare me just standing next to each other. And I don't know if the world knows this, they started this mess, and I was the first guinea pig daddy to go along with this."

Paris, 43, and Nicole, 42, recently teased a new TV project.

Lionel, meanwhile, still has vivid memories of their time on 'The Simple Life'.

He said: "When they first started doing things like driving down the freeway backwards and I kept saying, 'What are you guys doing?' [They'd say] 'It's reality television, dad!'

"And now these two are back together, oh my god, world, hang on to your seat. Thank god I'm older and my medication will get me through the next phase of our lives."

Meanwhile, Nicole recently revealed that she's having more fun than ever in her 40s.

The TV star has enjoyed lots of highs and lows in her life - but she's never been happier.

Speaking to Interview magazine, Nicole - who is married to Joel Madden - shared: "My 40s are the absolute most fun decade, and I find myself name-dropping my age now more than ever, simply because I want people to understand the state of mind that I'm in.

"I am not some 20-year-old idiot. I am a 42-year-old woman."

Nicole rose to prominence on 'The Simple Life', but she doesn't actually have vivid memories from that era of her life.

She said: "There are parts of me that just don't feel that far enough away from the early 2000s to think of it in any sort of distinctive matter.

"I've been called to do photo shoots and they say, 'Okay, and we want to do early 2000s,' and then I see the clothes and I don't remember that version of it at all."