Sket Dance has several references in both the manga and anime. In chapter 40, the character Switch yells "WWWRRYYYYYYYYYY" after the protagonist, Bossun, tells a boy named Yoshihiko that they're going to the park. "WRRYYYY" is a battle cry in the
JoJo series most commonly done by
vampires like
Dio Brando, but other characters like
Giorno do it as well.
In chapter 55, the character Roman Saotome draws a shojo manga featuring a character named Mariko Satonaka. Despite supposedly being a shojo manga, Roman's manga is more like a shonen, with Mariko summoning a Stand. Her Stand is called , which is a pun on "Rubber Soul".
In Chapter 220, Bossun rubs super glue all over his body which he thought was body cream. His body gets stuck in a bizarre pose, with another character telling him that he looks like he's from JoJo.
In Chapter 266, Minoru "Cherry" Sakura and his friends have a drink that turns them invisible only when they stop moving. While spying on his female classmates at the beach, he has to contort his body into a strange pose so that he doesn't turn visible. Bossun says that it's like watching a scene out of JoJo.
In Episode 71 of the anime, the character Noriyo Kuroda, also known as "Rodan", introduces himself by doing one of Giorno's iconic poses.
Chapter 40, "WWWRRYYYYYYYYYY"