Outlander’s Caitriona Balfe wished her onscreen husband, Sam Heughan, a very happy birthday on Friday with a sweet Instagram message you’ll want to see. The star - who has an amazing friendship with the Scottish actor - took to social media to send her best wishes to him on his 40th birthday. MORE: Who is Outlander's Sam Heughan dating: Everything he's said about love Caitriona posted a slow-motion clip of Sam goofing around on the set of their show, and pulling some sensational faces. WATCH: