This episode is a sidestory!  Gintama has been involved in many (one-sided) crossovers.  This time, they're working with the Jump comedy manga Sket Dance!  An episodic anime that airs on Thursdays at 6 PM about a group of three odd jobbers with plenty of laughs and tears...  Sounds very similar to Gintama.  As Gintoki warns that the Sket Dan is coming after Gintama, the Sket Dan members appear and offer a challenge!
They're the ones who dragged us into this... 
what are they trying to do?
Ellos fueron los que nos arrastraron a esto... ¿Qué intentan hacer?
Eles que nos arrastaram para 
essa... Querem o que agora?