Tell so many lies, so fast, your opponent hasn't the time or attention to address them, much less counter them, that's the Gish Gallopp. This successful technique is widely used against evolution, climate science, gun control, etc.
Conservatives have figured out a neat little rhetorical trick: One lie is easy for your opponents to debunk. Tell one lie after another, however, and your opponent’s debunkings will never catch up. By the time the liberal opposition has debunked one lie, there’s a dozen more to take its place. Science educator Eugenie Scott deemed the technique the “Gish Gallop,” named for a notoriously sleazy creationist named Duane Gish. The Urban Dictionary defines the Gish Gallop as a technique that “involves spewing so much bullshit in such a short span on that your opponent can’t address let alone counter all of it.” Often users of the Gish Gallop know their arguments are nonsense or made in bad faith, but don’t particularly care because they are so dead set on advancing their agenda. Unfortunately, the strategy is so effective that it’s been expanding rapidly in right-wing circles.
Thanks! It's worth going to Urban Dictionary and upvoting their definition -- whose example has a torrent of bullshit capped off with a half-truth.
(Coca-Cola was named for coca leaves and kola nuts, but Barbara Mikkelson at snopes.com explains that "When it first became general knowledge that cocaine could be harmful, the backroom chemists who comprised Coca-Cola at the time... did everything they could with the technology they had available at the time to remove every trace of cocaine from the beverage. What was left behind (until the technology improved enough for it all to be removed) wasn't enough to give a fly a buzz.")
In the Alternet article, Amanda Marcotte gives sensible advice for defending against the Gish Gallop:
There are a few tactics that help, including creating websites and pamphlets where all the lies can be aggregated in one place, for swift debunking. (Bingo cards and drinking games are a humorous version of this strategy.) A critical strategy is to avoid lengthy Lincoln-Douglas-style debates that allow conservatives to lie-dump rapidly during their speaking period, leaving you so busy trying to clean up their mess you have no time for positive points of your own. Better is a looser style of debate where you can interrupt and correct the lies as they come. I’ve also found some luck with setting an explicit “no lies” rule that will be strictly enforced. The first lie receives a warning, and the second lie means that the debate is immediately terminated. This helps prevent you from having to debunk and instead makes the price of participation a strict adherence to facts.
Related: "Debunking the Top 10 Most Egregious Republican Lies" (Alternet)
I like the debaters that accuse their opponent of doing this, and refuse to go to any other point until they have debunked the first lie. Don't know how it goes over with the general population, but I love it.