Straw man

Definition(s):
1. The Straw man fallacy is committed when an arguer A responds not to arguer B's stated argument but to a distorted, exaggerated, or misrepresented version of it. 
Arguer A attempts to refute arguer B's claim by confusing it with a weaker, less plausible claim (the straw man) and then attacking this weaker claim in place of the original one.
Pattern
1. Person A asserts P.
2. Person B substitutes Q (a distorted version of P)
for P.3. Person B attacks position Q.
4. Person B asserts or implies that P must be rejected.
=Example=
This ad against Prop. 8, "Gender auditors," commits the fallacy of straw man.
This ad against prop 8 "Home Invasion" commits a fallacy.
Description: Two representatives from the Mormon Church “enforcement division” intrude into a lesbian couple’s home, and state that they are there to take away their legal marriage rights. They take the couple’s wedding rings and rip up their marriage license.
“Home invasion.” Concludes it's wrong to forcibly enter people's houses. That doesn't decide the question of the right to marry
Pattern: 
: Person A: You shouldn’t vote for Proposition 8 because it will take away the rights of same-sex couples.
: Person B: You shouldn’t vote on Prop 8 because the Mormon Church will invade into same-sex couples’ homes and take away their legal rights.
: Person B: attacks the weaker argument that intruding into a couple’s home and stealing their legal rights is wrong.
: Conclusion: Therefore, we shouldn’t vote for Prop 8 because the Mormon Church will invade into same sex couples’ homes and take away their marriage rights.
Summary: 
Two members of the Mormon Church “enforcement division” invade a same-sex couple’s home. They take away the women's wedding rings and rip up their marriage license. The narrator then presents two facts: the first is that Proposition 8 will take away the rights of thousands of same sex couples; the second is that the Mormon Church is donating $20M to pass Proposition 8. Suddenly, the original argument (implicit) that same-sex couples should have the right to marry is replaced with another (also implicit): religious groups shouldn't be able to force their way into people' homes and make a mockery of their rights. The second argument is much easier to defeat that the first. The fate of the first argument doesn't depend on the fate of the second. The fallacy comes in pretending it does.
This ad for Prop. 8, "Proposition 8 commercial," also commits the fallacy of straw man.
=Other examples=
This interview clip of George Bush also commits the fallacy of straw man.
Description:
The arguer questions President Bush about whether he believes that "Americans and the rest of the world are beginning to wonder whether [he's] following a flawed strategy" as they start to "doubt the moral basis of [the] fight against terrorism." Bush then avoids actually answering the question by focusing on Americans' compassion and how it is unacceptable to compare their actions to those of religious extremists who killed innocent women and children. He misrepresents what is being asked by saying that the arguer is comparing Americans to religious extremists.
Person A:  The world is beginning to doubt the moral basis of the fight against terrorismPerson B: There is no connection between the compassion of the American people, and the actions of Islamic extremists.
Person B "proves"(this term is used very, very loosely) that there is no similarities between Americans and terrorists. This ignores the original statement of America/the World is beginning to doubt the basis of the fight against terrorism.
Therefore, Person A's position(x) is false/incorrect/flawed because Person B's misrepresented view of x, is false. Essentially: Because there is no similarity between Americans and terrorists, the world isn't beginning to doubt the fight against terrorism.
Colin Powell made a statement about the world beginning to doubt the moral basis of the war on terrorism, and a reporter questions Bush on whether he believes that, perhaps, Americans are also starting to believe that he is following a flawed strategy. Bush then responds to the question with an answer that does not follow the original question. He uses a distorted argument and says that it is unacceptable to compare American actions to those of religious extremists.
This ad against Obama's health care plan Old People, Fat People creates the straw man fallacy.
Description: A satirical song that opposes Obama’s health care plan by suggesting that the plan would cut off elderly and overweight people. The song replaces "short people" in the song "Short people got no reason to live," with “old people and fat people.” "Old people got no reason, fat people got no reason, got no reason to live." The ad replaces question of health care reform with question of whether old people and fat people have the right to health care.
Pattern:
: Person A: The extremely high cost of health care needs to be reduced with ineffective additional expenses.
: Person B: Old people and fat people are too expensive to take care of and have no reason to live.
: Person B: Attacks the fact that old and fat people have too many needs to maintain that will cost extra money and aren’t worth the extra additional expenses.
: Conclusion: Therefore the health care reform should not have to be responsible for old and fat people, because their needs are too expensive to maintain and it’s not important if they die.
Summary: 
The song accuses Obama and other advocates of health care reform of rationing care and, in particular, of limiting care to elderly and obese people. It attributes to Obama the belief that "old people and fat peple got no reason to live." He gives a variety of reasons why old and fat people would have additional expenses put on the health care reform, such as needing new hip replacements, new drugs, and expensive machines and hospital tests. He argues that old people are “unproductive anyways” and that fat people are “bad luck”; they move too slow and build up in heart disease and cholesterol. The straw man fallacy is committed when the original argument (implicit) that health care reform is wrong is replaced with another: Killing elderly and obese people is wrong. This second argument is much, much easier defend. Settling the question of whether it is wrong to kill large groups of vulnerable people does not, however, settle the question of whether health care reform, as currently proposed, is wrong.