Selma Blair dived naked into her swimming pool to get her own back on her son

Alongside two pictures of the moment, Selma wrote on Instagram: "I sometimes doubt my child's ethics. "Preparing to dive.

"A very big deal for me. Instead, I felt a tiny hand on swimsuit and lost any coordination.

"#Terror #PunkKid #PayBack is coming. Any ideas?"

The 'Legally Blonde' star later uploaded a shot of her nailing the dive with her bottom proudly on display.

She quipped alongside the bare shot: "Victory. I don't give up. #bottomsup my boy is a #crackup @kidarthursaint (sic)"

Meanwhile, Selma recently admitted she is "humbled" by the support she received after revealing she's battling insomnia as a result of MS.

The actress has been open about her struggles with MS since she was diagnosed with the condition last year, and she had shared a photo of her legs covered in bruises and admitted she is "afraid" of what's happening to her body.

The 'Cruel Intentions' star later took to Instagram to thank her fans for the overwhelming kindness they've shown her and insisted that although she can occasionally become "overwhelmed" with the reality of her condition, she no longer feels "ashamed to be so transparent " about her illness.

Selma - who has Arthur with her ex-boyfriend, fashion designer Jason Bleick - wrote: "It is darkest before the dawn, I have always heard. And I keep it in mind. And I still get overwhelmed in the chaos of the dark. And I am so deeply moved at how many people called or wrote or left comments after my last post.

"The old me was ashamed. Ashamed to be so transparent with vulnerability or fear. And I wanted to delete the image. The heart bruised words. But you all changed that with your words of support. I was humbled.

"I couldn't even read til now. Thank you. Thank you.maybe I will print and put in a book for when I need it again. We should all do that sometimes. (sic)"

The 'Hellboy' star went on to profess that she "will get there" in regards to accepting her condition and once again thanked her fans for their kind comments.

She wrote: "Thank you universe. I will get there. Have patience. Thank you. All of us. Be gentle. With ourselves and others. It is a wonderful feeling. Thank you to everyone here and in my life who did that for me the last few days. I can do this now. (sic)"