As CNN explains, spider webs can block the air conditioner's drainage tubes, which causes water to collect in the airbag's control module. Apparently, the water has caused some control modules to short circuit, triggering dashboard warnings in at least 35 cars and, in three cases so far, causing the airbag to deploy.
According to Toyota spokeswoman Cindy Knight, spider webs are the only consistent cause of the blockage. So, basically, if you're driving a 2012/2013 Camry, Venza, or Avalon, you're doomed to...well, you're probably fine. But still, spiders! And this isn't the first time spiders have forced a car company to issue a giant recall. In 2011, Mazda recalled 52,000 Mazda6 sedans because spider webs were blocking the gas tank's vent lines.