Among the scores of Instagram pictures of food, cleavages and pets, there was a special image worth getting excited about on Wednesday night.

Danny Masterson revealed that the cast of That '70s Show are still in touch - and had met up to enjoy an impromptu sing-a-long.

"Every once in awhile friends gather for a 6 part harmony of a BigStar song..." he wrote.

The actor, who played Hyde in the retro sitcom, caused an internet stampede of comments and retweets as the snapshot went viral.

BigStar were soft rock band popular in America during the 1970s, and were also responsible for That '70s Show's theme tune.

Joining him for the musical date were Ashton Kutcher, Mila Kunis , Topher Grace and Wilmer Valderrama.

Laura Prepon, who played gravel voiced Donna Pinciotti in the show, also shared the photo, and added: "We need Santa hats and caroling books. ...And for it not to be almost Xmas already! #luvmygang#70s-hang.

Fans will be hoping that the reunion will help drive the cast to film some more episodes of the popular show, which ran from 1998 until 2006.

Mila has previously revealed that she had such a great time filming the retro sitcom that she would jump at the chance to revive her character, Jackie Burkhart.

Earlier this year, she told E! News: "I'm more than game for it. I've said it before — I would love to do it…Yeah, I would totally do it.

"Why not? I loved it. It was eight years and they were eight amazing years of my life."

When Mila, now 30, auditioned for the role she was just 14 years old, and lied to the show's producers that she was four years older.

Thankfully for her they found her ruse amusing and let her keep the part, where she went on to meet LOHL (love of her life) Ashton.

One younger member of the cast who would have been sorely missed from the get together is Lisa Robbin Kelly , who died a few months ago.