Adam and Eve were two individuals that Clyde Langer compared himself and Rani Chandra to when the rest of the human race disappeared from the Earth, leaving them as the only two. (TV: The Empty Planet)
While pretending to be Rose Tyler, Cassandra O'Brien.Δ17 borrowed what she thought was a 21st century colloquialism, and said "I can't Adam and Eve it." (TV: New Earth)
While pretending to be a native 19th century Londoner, Strax used the phrase "Can you Adam and Eve it?" Jenny had been giving him "assimilation training" lessons, which he was happy to put to use in the subterfuge. (AUDIO: The Cars That Ate London!)
Behind the scenes
Adam and Eve, in the Bible, were the first humans created by God after he created the rest of the world. They lived in the Garden of Eden before getting banished; according to Christian theology, due to original sin.
"Adam and Eve" is also Cockney rhyming slang for "believe".
The Doctor Who Adventures comic story Save the Humans! featured colonists Adam and Steve.