Former US President Barack Obama donned a santa hat on Thursday (14 December) to surprise kids at a Washington DC youth club, sending social media into a lovefest for the 44th President of the United States.

"There's no better time than the holiday season to reach out and give back to our communities," Obama wrote on Twitter. "Great to hear from young people at the Boys & Girls Club in DC today."

The accompanying photo showed Obama cross-legged on the floor and smiling with a baby in his lap, while other children grinned for the camera.

A video shared by his communications director, Katie Hill, showed kids reacting with excitement at the former president, who surprised them, arriving with a sack of presents slung over his shoulder.

Replying to the tweet, one woman said she was the mother of one of the children in the pictures. Describing the effect of the surprise from the former President she said her son "talked about the visit all evening. 7yrs old and was impacted incredibly."

The Boys and Girls Club of America is a national organisation providing after-school programs for young people across the United States. In a tweet, the organisation thanked Obama for "surprising Club kids", along with the hashtag #greatfutures.

"You are such an awesome human being," read one reply to Obama's post, while another wrote: "Thank you President Obama for continuing to give back to the communities that you have so deeply inspired."

At the time of writing, that tweet had been retweeted over 44,000 times and liked nearly 300,000 times. Though not a regular Twitter user, the former president dominated the top tweets of the years for 2017.

One he posted when America reeled from the aftermath of a white supremacist march in Charlottesville, Virginia has so far been retweeted over 1.7 million times.

Along with a picture of Obama greeting some babies at a window, the post quotes Nelson Mandela saying: "No one is born hating another person because of the colour of his skin or his background or his religion."