Vin Diesel accepted the ALS Ice Bucket Challenge on Monday, Aug. 18, and followed up his challenge by posting a racy naked photo of himself in the shower.

Vin Diesel Takes The ALS Ice Bucket Challenge

Diesel, who was challenged by his Guardians of the Galaxy director James Gunn, posted a few short videos to Instagram accepting the challenge. Diesel also issued Gunn a challenge of his own: “Plant a tree for Groot.”

Diesel plays Groot, an alien, talking tree, in Guardians of the Galaxy, and previously shared videos of himself planting a tree in honor of his character.

After dumping a bucket full of ice on his head, the unflinching action star nominated First Lady Michelle Obama, Angelina Jolie and Vladimir Putin to take part in the Ice Bucket Challenge.

Vin Diesel Shares Sexy Post-Challenge Pic

Soon after, Diesel shared a risqué photo on Facebook. In the photo, shot straight on, Diesel stands tall, and presumably naked, in the shower. The photo ends, keeping Diesel from going full frontal.

Zoe Saldana Confirms Pregnancy In Ice Bucket Challenge

Gunn also challenged Guardians of the Galaxy actress Zoe Saldana, who accepted, but said she was unable to complete the challenge because she is pregnant. Instead, her husband, Marco Perego, bravely took the challenge for her.

“Obviously, I can’t do it myself,” Saldana teases in the video, showing off her pregnant belly in profile for the camera.