People Who Say that Santa Doesn’t Really Exist Actually Want to Believe in Him / Prayer Won't Make Your Worldly Desires Go Away! Control Yourself

Gintama.: Slip Arc · Episode 37 · “People Who Say that Santa Doesn’t Really Exist Actually Want to Believe in Him / Prayer Won't Make Your Worldly Desires Go Away! Control Yourself”

Consists of episodes animated from unused manga chapters, before returning to the Silver Soul Arc on January 8, 2018. Porori is an Onomatopoeia for something (mainly water) falling.