When we read the sakhis we understand the great sense of humor of Guru Nanak Dev ji. Imagine him telling the Brahmins that if he throws water to the west it will reach his cattle. What a stark way of telling them that they were deluding themselves. There are so many examples of his wit...which he used to teach a moral principle in a very clear way.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/sikh-sikhi-sikhism/29583-celebrating-sikh-smiley-art-mai-harinder.html

Our Gurusahiban were not dry sticks without humor. Nor could they inspire thousands as they did in their day without "spirited" personalities.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=29583

At SPN we try to provide a complete diet for the mind, body and soul. Humor is an essential ingredient.