Thousands of kids and adults across the UK are going to be wearing odd socks on Tuesday 12 November and there's a really good reason why!
It's as part of Anti-Bullying Week - this year's theme is 'change starts with us'.
Odd Socks Day is a national event all about celebrating what makes someone unique.
It's organised by the Anti-Bullying Alliance which is a group of organisations, charities and individuals who work together to try and stop bullying.
Are you doing Odd Socks Day today? We'd love to see a photo!
People are being encouraged to wear their favourite odd socks (yes, this means picking out a pair that don't match!).
It's to symbolise that we are all different and that children should be themselves, accepting of one another and celebrate difference.
Martha Evans, Director of the Anti-Bullying Alliance, said: "Bullying is an incredibly serious issue and to see so many parents, teachers and children involved with the campaign each year sends a powerful message."
CBeebies presenter Andy Day is supporting the campaign with his band Andy and the Odd Socks.
They've released a song called Change - it's aimed at kids and highlights how one simple change can help tackle bullying.
Andy said: "Me and the Odd Socks are super excited to lead the way for Odd Socks Day once again. 'Change Starts With Us' is such an important theme to highlight for this year's Anti-Bullying Week, as we spread the message of mindfulness towards the way we treat others. We're looking forward to seeing the impact of this year's campaign and cannot wait to see everyone rock out with their socks on!"