The London Underground conveniently closes at night from around 0030 to 0500 (because obviously everyone's asleep then).

Catching a 'tube of shame' is when one catches one of the early morning services home after a particularly massive night out, or worse one-night-stand.

The 'shame' is normally attributed to a combination of a comedown/hang-over you have and the reflection time you have on the train as you piece together what actually happened the previous night and how to explain it to friends.
Johnny answers phone
Ben: "... what were you doing last night with that girl/boy?"
Johnny: >>No comment<<
background noise of street/trains etc...
Ben: "Where are you?"
Johnny: >>no comment<< (too hung over, tired/mashed)
Ben (smirking): "Tube of shame :)"
Johnny: >>laughs in acknowledgement and hangs up<<
by cerberus82 February 12, 2011
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