I'm surprised Mudcatters don't know this. Valderi was an early 19th century brand of outdoor sporting equipment, manufactured in Italy but owned by a Lithuanian named Firgit Valderius. The song was originally written for an ad campaign, implying that the hiker likes his Valderi brand knapsack so much that he sings about it and breaks into exhilarated laughter. The song was popular but didn't help sales, and the company went out of business soon after.