I must admit that I am still encountering difficulties understanding Earth humour, but I shall attempt to fathom the meaning of this comic strip nonetheless.

Kah Ek is a Viking, yet he works in a regular office. His tardiness, which, judging by Eric's casual reaction to Kah Ek's grandiose attempt to excuse it, would seem to be a recurring problem. Therefore, Kah Ek's tales of grand journeys and hard-fought victories against dreaded foes such as "Lord Chaffinch" (who may or may not actually exist) are met with jaded disbelief by his boss and/or co-workers, because they perceive these accounts merely as further efforts on Kah Ek's part to deflect attention from the real problem, which, of course, is his "lateness" at "signing on."

I therefore conclude that this highly improbable contrast between Kah Ek's apparently authentic Viking appearance and demeanor, and the ordinary, everyday aspect of his employment situation, is intended to evoke what is commonly known as an involuntary "laugh response" in the reader.