Caitriona pokes fun at birthday boy co-star Sam

CAITRIONA Balfe proved her bond with her Outlander co-star Sam Heughan is just as strong off-screen as she took to Twitter to share an amusing birthday tribute to the actor, who turned 37 yesterday.

In one jokey tweet, the Monaghan actress, 38, penned: ‘Twitter just asked what’s happening... and I can safely say I have no idea !!!! Happy Birthday our kid.’

Beneath that, the Super 8 star shared a behind-the-scenes snap from their show, left, which showed the Doctors actor sticking his tongue out at an amused Caitriona. The model also posted a meme of the Island at War actor, who joined thousands to run the 26-mile Stirling marathon in Scotland on Sunday.

In the snap, the screen star sported a sweaty look, edited with the speech bubble: ‘I like getting my nails done!’

Alongside the meme, Caitriona penned: ‘Who da best.. ????? Always pamper yourself on your birthday. Especially if you’ve just crushed a marathon!!! @SamHeughan #ipromisei’ll stopnow.’

Sam – who completed the race in three hours and 15 minutes – helped to raise £16,000 (€18,200) for Cahonas Scotland.

They pair were hard at work shooting season four of their critically acclaimed show for the past few months after a gripping series three finale of Outlander.

Viewers were left on the edge of their seats when Claire and Sam Heughan’s character James landed on the shores of America after battling an epic shipwreck.

Season four is an adaptation of the fourth book in Diana Gabaldon’s series of novels – Drums Of Autumn.