Definition - Military Slang
Slang military phrase, usually ironic in use. A soldier might use it after seeing someplace he hasn't been before. Origins are proably Vietnam era, among Airmobile assault units.
A soldier is being medivaced out of an LZ by helicopter, having been wounded in a firefight. If he was unfamiliar with the medic that treated him, he might say "Thanks for the tour!" as a parting salute as he was led away.
As he was being escorted to the transport helicopter, Timothy McVeigh supposedly said this to the US Marshal who was his keeper during the Murrah building trial.