Linus does it too, he'll sniff at the freezer ( on bottom)and has jumped in more times than I can recall, makes me wanna throw him in a snowbank to see what he'd do...heehee
Open the door, and Molly is guaranteed to appear, mewling and perching her front paws on the bottom shelf. She doesn't so much sniff around, she just understands that the fridge is where food comes from, and always has to come see it up close. Buffy also comes running when the fridge opens, but she figures mealtime is coming so she hops on the counter and then on top of the fridge (where she usually eats; drives my family crazy). Willow, the ADD-Ghost, does her usual appear-here-there-here-there-here-where?, but the circle of randomness is much closer to the vicinity of the fridge, lol
When Molly is nosing around in the fridge, my dog, Jake, is usually doing it too. Fortunately everyone's good about backing away from the fridge so I can close the door.