A phrase usually uttered at innocent pedestrians. The joke stems from pretending you are looking for the lost snowboarder Damian, which is why you will hear this phrase commonly on ski slopes.
The story originates from the stories of snowboarder Damian Leonard, who stated that he often was left by his ski mates due to his low skill level. His friends would then yell Damian at passing skiers/snowboarders as if his friends thought the passing people were him.
The "uh uh uh" section was added to imitate being close to either death or sexual climax while looking for Damian.
Person: "Uh, Uh, UH DAMIAN!"
Skier: "Bruh"