The significance of Martha Cooper for the graffiti and street art scene does not need to be explained here. Yesterday, the following call was published in the social media:

Dear all,
Martha Cooper will be 80 years on 9th of March. So we invite everyone to paint a Martha piece to this date on walls, trains etc. around the world to appreciate her impact on the scene.
Also the idea is everyone is spreading this call to action to all their graff friends, so feel free to copy this message and share it in private chats.
To collect all the photos, you can send your photo to this email: MC80birthday@tutanota.com
(If you also use a tutanota email, it will automatically be e2e encrypted.)
On the 9th 10pm (CET) we will create a wetransfer folder for Martha and deliver it to her.
And if you also want to upload and share your piece on Instagram you can use the hashtag #marthacooper80