Tunnels of a silly sort

While many in the eastern part of the country (justifiably) despaired over tunnels that once got them where they wanted to go but are now impassable thanks to Hurricane Sandy's devastation, I (rather guiltily) pored over photos of tunnels of a more joyful sort.

Far from crowded corridors for commuters, Bubby and Mac know tunnels as nothing more than colorful tubes of pure pleasure. Tubes that are always in operation. Tubes that are doubly delightful when shared by two.


Today's question:

When did you last go through a tunnel of any sort?