Elon Musk replaced Twitter's blue bird logo with the Shiba Inu logo related to Dogecoin, the replacement of the logo was Musk's way of retorting back to the lawsuit filed by the Dogecoin investors against him.
The step was taken by Musk a day after he appealed for dismissal of a $258 billion racketeering lawsuit which accused him of inflating the value of Dogecoin intentionally.
The lawsuit was filed by Dogecoin investors against him, and Musk's legal team argued that his tweets regarding the cryptocurrency were 'innocuous and often silly.'