Bad Wolf meme
"Bad Wolf" was a repeated meme throughout Rose Tyler's travels with the Doctor through space and time, mostly throughout her travels with his ninth incarnation, but partly throughout her travels with his tenth one also.
Timeline
Ninth Doctor's era
The phrase was most commonly found in graffiti during the 20th and 21st centuries (DW: Aliens of London, Father's Day, The Parting of the Ways), but the first chronological occurance was in 1869, in which Gwyneth, a parlour maid and clairvoyant, looked into Rose's mind and declared that she had seen "The Big Bad Wolf". (DW: The Unquiet Dead)
However, the first occurance of the phrase in the Doctor's and Rose's timestream was in the year 5,000,000,000 on Platform One orbiting the soon-to-be-destroyed Earth, in which the Moxx of Balhoon told the Face of Boe that the current situation was "the classic Bad Wolf scenario". (DW: The End of the World)
It was also found in other languages - it was used in relation to a Nazi bomb used in World War II, the "Schlechter Wolf" (DW: The Doctor Dances), and to a nuclear power station, built in September 2006, the "Blaidd Drwg" power station. (DW: Boom Town)
Many companies also used the phrase "Bad Wolf", such as GeoComTex, who used it as their helicopter call signs, for example Henry van Statten's private helicopter was "Bad Wolf One". (DW: Dalek)
The phrase became more common in the years 199,909 to 200,100, in which the Dalek-controlled Badwolf Corporation and the television channel "Bad Wolf TV" made use of the phrase. (DW: The Long Game, Bad Wolf / The Parting of the Ways)
It was later shown that, to save the Doctor's life, Rose Tyler had opened the Doctor's TARDIS, looked into its heart, and become the Bad Wolf. She had then used her near-supernatural powers to destroy the Dalek Imperial Fleet and spread the Bad Wolf clues throughout space and time, so she would eventually realise she could use the TARDIS to save the Doctor (thereby creating an ontological paradox). Rose was later restored when the Doctor saved her life by taking the Time Vortex energy from the Heart out of her body and regenerating. (DW: The Parting of the Ways, Children in Need special)tHE WEREWOLF SAID THAT ROSE HAD A BIT OF THE WOLF IN HER HE WAS REFFERING TO THE BAD WOLF
Tenth Doctor's era
After the revelation of their significance, Bad Wolf occurrences became less common in the Doctor's and Rose's timestreams, although they still occurred.
In 1879, the Host, a Werewolf, stated that Rose had "something of the wolf about her" (DW: Tooth and Claw). The Torchwood files on Rose had been corrupted by the "Bad Wolf" computer virus (DW: Love & Monsters) and, after the Doctor and Rose had been separated in different universes, the last hole through the Void linking them led into "Dålig Ulv Stranden" - Bad Wolf Bay - in Norway. (DW: Doomsday)
Websites
Many websites also made use of the phrase "Bad Wolf", such as the UNIT website (unit.org.uk), which had "badwolf" as the password to one of its secure areas, and a clip on Mickey Smith's website identified the newsreader who reported the spaceship crash into Big Ben tower as "Mal Loup", French for "Bad Wolf". Micky also described the Doctor on the same site as "making another decision for us, all 'I'm the big bad wolf and it's way past your bedtime.' "
(whoisdoctorwho.co.uk)
On the FAQ of the Geocomtex website the correct sequence of the pins in the first question is morse code for badwolf.