US President Donald Trump was at his blooper best when he mistook Good Friday for Easter and wished the world 'Happy Good Friday', triggering an avalanche of criticism from Twitterati who tore into him for his embarrassing gaffe.

Good Friday refers to the crucifixion of Jesus Christ and is a day of mourning for Christians around the world. Easter, on Sunday, marks the celebration of Christ's resurrection. The good in Good Friday refers to the day being holy.

Trump took to Twitter on Friday and wrote: 'HAPPY GOOD FRIDAY TO ALL'.

The tweet did not go down well as many people slammed the US President for his basic lack of knowledge.

'Just another evidence you know absolutely NOTHING about Christianity. There's nothing happy about Good Friday. Wait for Easter Sunday,' said one of his followers.

'This is a solemn day for Christians. It's not called Happy Friday. Like not knowing what the significance of Pearl Harbor was, I'd suggest the President doesn't know what happened on Good Friday according to the scriptures,' wrote another.

'Uhm if you ever walked into an actual church, you'd know today is one of the most somber days in the church year. You can't even get Christianity right,' tweeted another.

However, at his daily White House news conference on coronavirus, Trump on Friday, while giving an an update on the war against coronavirus, told reporters that millions of Christians celebrate Easter and the resurrection of Christ.

'Thank you very much everybody, and good afternoon. Today is Good Friday. And this Sunday, millions of Christians celebrate Easter and the resurrection of Jesus Christ.

'At this holy time, we pray that God will heal the sick and comfort the heartbroken and bless our heroes. As American families look forward to Easter, we're reminded that our story ends not in despair, but in triumph and renewal. Very appropriate, isn't it?' he said.

President Trump is known for his gaffes. In April last year, he erroneously wrote that '138 million people' instead of 138 were killed in a string of blasts in Sri Lanka.

Trump is known for for using embarrassing nicknames as well as 'mispronouncing names' of people such as 'Jeff Bozo' in reference to Jeff Bezos of Amazon.

In March last year, he mistakenly referred to Apple CEO Tim Cook as 'Tim Apple', a verbal slip which netizens poked fun at by sharing rib-tickling memes on social media.

Before that, he had called Lockheed Martin CEO Marillyn Hewson 'Marillyn Lockheed.