Saying "don't step in the..." followed by another word is a non-vulgar way of equating the thing denoted by that other word with shit. Used to good effect in the title and cover illustration of the Dilbert book known as "Don't Step In The Leadership".
(Another sense of the phrase makes it shorthand for don't step on your dick.)
"This is my boyfriend's roommate's 'studio'. Don't step in the art."