Rationality anecdotes for the homepage?

In the com­ments for The Cog­ni­tive Science of Ra­tion­al­ity, Spur­lock said

The be­gin­ning of this post (the list of con­crete, pow­er­ful, real/​re­al­is­tic, and avoid­able cases of ir­ra­tional­ity in ac­tion), is prob­a­bly the best in­tro­duc­tion to x-ra­tio­nal­ity I’ve read yet. I can eas­ily imag­ine it hook­ing lots of po­ten­tial read­ers that our pre­vi­ous at­tempts at in­tro­duc­tion (our home page, the “wel­come to LW” posts, etc) wouldn’t.

In fact, I’d nom­i­nate some ver­sion of that text as our new home page text, per­haps just chang­ing out the last cou­ple sen­tences to some­thing that en­com­passes more of LW in gen­eral (rather than cogsci speci­fi­cally). I mean this as a se­ri­ous ac­tion­able sug­ges­tion.

There are cou­ple prob­lems with us­ing the spe­cific anec­dotes from the post:

  • It would make the be­gin­ning of the post seem bor­ing for any­one who had read the home­page.

  • There has been dis­cus­sion on LW that the sunk cost fal­lacy may not be much of a fal­lacy in prac­tice, and com­menters on the post were also skep­ti­cal of the rare dis­ease ex­am­ple.

But the idea of start­ing our web­site off with con­crete ex­am­ples, the way Eliezer re­cently recom­mended start­ing off es­says, seems like a good one.
So what are some quick, con­crete, com­pel­ling sto­ries about how ir­ra­tional­ity sucks/​ra­tio­nal­ity rocks that we could put on the home­page? Bonus points if the story is straight from a study, or is a true story that hap­pened to you or some­one you know.