On a new episode of 'The Martha Stewart Podcast,' Kate Hudson opened up about her oldest son Ryder Robinson's tattoos and revealed which "terrible" one she hates the most.

Kate Hudson, Cara Delevingne and Mandy Moore were among the names supporting the non-profit ... Cara Delevingne opted to show off her tattoos in an incredible feather and lace black number.

Kate Hudson is by no means anti-tattoo, but even she's seen some art that made her "draw a line in the sand as a mother." The culprit? Her oldest son Ryder Robinson, who apparently got a "terrible" ...

The actress said she's lenient about letting her kids get inked, but admitted that this particular one was the exception Kate Hudson doesn't subscribe to a tattoo-free household, however ...

Kate Hudson doesn't subscribe to a tattoo-free household, however, she does have boundaries about the kind of ink her kids get. "Ryder got a tattoo that I hate so much," Hudson admitted to host ...