In "Bing! Bam! Boom!", Tuffnut says that their parents "took our pet yak Sam out to the farm, to live." We can presume that means Sam is actually dead. To make things worse, Ruffnut adds that if it weren't for the delicious yak steaks they ate for dinner that night, they might have been more heartbroken about Sam no longer living with them. Tuffnut continued on how they also enjoyed the steak dinner while wearing new jackets. So not only did Sam die, but they ate him, and their parents also made fur coats out of him. The Twins did not connect these new things with Sam's absence.