Chelsea Handler helped Sandra Bullock celebrate her birthday with a cowgirl themed night out on Thursday (24.07.14).

The actress reached a half century on Saturday (26.07.14), but kicked off her celebrations at the Million Dollar Cowboy Bar in Jackson Hole, Wyoming, with a group of female friends including the chat show host.

They checked out a performance by country group Southern Soul Allstars.

A source said: ''There were probably six to 10 women in the group. It appeared to be a ladies night. They just came in to listen to the band.

The onlooker added to E! News: ''It was pretty low key. They all had one drink...and were all dressed casually.

''Sandra looked radiant, beautiful and was very sweet. It looked like she was having a blast.''

Sandra and Chelsea have been close friends for years, and on Saturday night, the 'Chelsea Lately' host posted a picture on Instagram of a group of women in a cheeky pose, with one of the group showing off her thong-clad butt, though it is unclear as to her identity.