Greta Thunberg has made fun of Donald Trump's election reaction urging the president to "chill" in a message on Twitter.
Mimicking a tweet the president aimed at her last year, the climate activist also said he should work on his "anger management".
Her tweet was a response to Mr Trump's call on the social media site to "stop the count".
The 17-year-old tweeted: "So ridiculous. Donald must work on his anger management problem, then go to a good old fashioned movie with a friend! Chill Donald, Chill!"
The post was a parody of the president's words in December last year after the campaigner was named Time Magazine's Person of the Year.
Mr Trump wrote: "So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!"
Not one to sit back and ignore the president's flippant comment, Greta responded shortly afterwards by changing her Twitter bio by describing herself as: "A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend."
Mr Trump has received widespread criticism for his reaction to how the election results are slowly panning out.
On Thursday the results were too close to call almost two days after polls closed.
The Democratic candidate said he feels "very good about where we stand" and that he has "no doubt" he will be declared the winner.