Teenagers will be told to "stand up for their elders" on public transport -- or risk losing their right to free travel. London Mayor Boris Johnson will declare plans today to make youngsters sign a "courtesy pledge"    to promise to behave in a respectful manner when travelling in the capital. The three-point pledge states that they will give up their seats to the elderly, pregnant and disabled; keep from using offensive or threatening language; and be courteous and polite to fellow passengers and staff. Those who refuse, or are caught behaving in a _ manner, will have their free travel passes removed. The plan -- a key part of Mr. Johnson's re-election bid-- will initially affect the 400,000 ll-to-15-year-olds in London who qualify for free travel cards, but Tory sources believe the idea could be used across the country. A Conservative insider said: "The plan corresponds perfectly with the push to create a Big Society. It is about changing culture and expectations around behavior to improve the atmosphere on buses and trains for everyone." Speaking before today's launch, Mr. Johnson said he was determined to deal with the anti-social behavior of a "minority of youngsters" on public transport. "When I was a boy, I was taught to stand up for those less able to, "he said. "Youngsters enjoy the privilege of free travel, which is paid for by Londoners, but they have to understand that with that privilege comes responsibility. Anyone who abuses this privilege will have it taken away, and will have to earn that right bach ." Teenagers found guilty of a serious violation of the new behavior rules will lose their travel passes, and will have to carry out unpaid community work to earn them back. Mr. Johnson is also introducing a "two strikes and you're out" policy to deal with repeat offenders, under which those committing a second serious violation of the rules will lose their travel rights permanently. According to Mr Johnson,  _  .
youngsters should know duty comes with benefit youngsters shouldn't use the privilege of free travel anyone shouldn't make money with the privilege youngsters should do some unpaid community work