UK 
United StatesIf someone in London told you they were taking a tube to work, you wouldn't think much of it. But in Boulder, Colorado, the phrase comes with a whole different meaning.
Commuters take a very different tube to work
HR Grapevine
If someone in London told you they were taking a tube to work, you wouldn't think much of it. But in Boulder, Colorado, the phrase comes with a whole different meaning.
