Randall is giving reason number 58 why he should not have children. We see fictitious "father Cueball" talking about the Wikipedia entry for the list of fatal cougar attacks in North America. Here's the link so you can look for yourself.
And the reason he should not have children is the fact that he can't resist himself when learning and sharing knowledge about the world (from Wikipedia).
When you have kids and you learn scary things, you should not share it with them. You should also not share new info in a manner that would cause nightmares, sleeplessness, or other psychological problems in your kids, as the title text suggests.
- [Cueball is sitting at a computer; a child is standing behind.]
- Cueball: Whoa, ever seen Wikipedia's list of people who were attacked and killed by cougars?
- Cueball: Crazy how many of them were kids who were just playing outside their houses.
- Reason #58 I should never have children: My love of learning and sharing knowledge about the world.