These two sides add up to six dots, which the boys in the lab tell us is less than seven.
And then throwing them in this specific way:
"Use an underhand motion, as though you're not completely comfortable with the use of human limbs."
The idea is that the dice land flat on the table, transferring most of the energy to the table surface. By the time their journey reaches the table edge, they're exhausted and just want to lay down with a good book, so the pyramids just sort of nudge them instead of bouncing them around.
Apparently, the theory is sound if you can do it correctly. A guy with the pseudonym "Stanford Wong" joined the seminar, practiced 5,000 throws, then bet people he could beat the odds and roll less than 80 sevens in 500 rolls. He rolled 74 sevens and won $15,400. Stanley Fujitake is another person who claimed to master the robotic precision required, and by "claimed" we mean he made $30,000 rolling the dice for 3 hours straight -- 118 rolls without rolling a seven.
Simultaneously winning the award for World's Most Tedious Bar Trick.
Of course, there's no magic trick here (other than "get really good at rolling dice") and you probably have to be willing to lose a shitload of money while you practice. Unless you buy your own craps table to practice on, we suppose, but there's a good chance that's going to result in your family staging an intervention.