The lizardman and gorillaman are right about not being able to tell what kind of trunks you get. All of the other trunks on the wheel have at least a vague clue hinting at which animal they could be. The trunks you got are completely bare, though. The suspense will be over soon enough.
The transformation happens almost as quickly as it did for Tom Murray. As soon as you put your foot into a leg opening, it shifts into a bear's foot. Skin disappears under brown fur. Black claws appear on your toes. You jerk your foot back out at the sudden tingly, heavy sensation, but the changes don't recede at all. You can't turn back now, so you shove the rest of your leg through the leg opening. Your leg tickles as the fur grows near instantly.
You shove your other leg through the trunks. The changes are the same as the first. You can already feel that your legs are thick with muscle.
Pulling the trunks up gives the rest of your body the signal to change. Fur shoots up your body and down your arms. An increase in bulk and muscle mass follows the fur. The palms of your hands become dark and padded. You feel your new stub of a tail grow over the back of the trunks. The muscles in your arms bulge, and your shoulders widen. Your mouth stretches out into a distinctly bearish muzzle. You can feel that your ears are much higher on your head.
The fat on your bear belly doesn't bother you. It just makes you harder to pin down. In fact, there isn't much of a disadvantage to this body in a wrestling match at all. Bears are natural wrestlers. Sharp claws and teeth, enormous strength and size, better sense of smell than a bloodhound... Weaknesses? WHAT weaknesses? When the changing screen falls away, you show off your luck with a confident bear roar.
You hear a lion roar and an elephant trumpet. "An omnivore!" they say at the same time, both disappointed.
"And now for your first match..." says the gatorman.