An alternate form Luigi takes on when using the super acorn. In this form, his overalls become green and his shirt becomes grey and has a notable turtleneck to it. His usual hat also gains a pair of fake squirrel ears and he also has a fake squirrel tail, as well as a membrane between his arms and his back reminiscent of real world flying squirrels. His shoes also become grey, similar to his shirt.
This tag implicates luigi (learn more).