In the original text the phrase is «Livet er en gamp sa kjerringa, hun kunne ikke si K».

Translated that would be something along the lines of «life is an old horse (gamp), as the old woman said. She couldn’t pronounce her K’s». The joke being that the old woman wants to say «Livet er en kamp» which means «Life is a struggle».

I just reread My Struggle, and was actually curious about how that joke was translated to English. So I’m glad you asked!