“SYSK’s 12 Days of Christmas… Toys: How Yo-Yos Work”

Podcast: Stuff You Should Know
Hosts: Josh Clark & Charles W. “Chuck” Bryant
Date: December 12, 2025

Episode Overview

In this festive episode, Josh and Chuck dive deep into the history, physics, and cultural significance of the yo-yo. With their trademark blend of humor and curiosity, they unravel how yo-yos work and explore the toy’s surprising depth—from ancient origins to modern engineering twists. Expect nerdy enthusiasm for physics, tales of yo-yo pop culture, and plenty of classic SYSK banter.

Key Discussion Points & Insights

1. Origins and Etymology of “Yo-Yo”

• The word “yo-yo” is traced back to the Filipino language, where it means “come, come” or “come back” (06:23).
  • Josh: “The word yo yo as it stands means come, come, or come back.”
• The modern usage of “yo” as an interjection predates the 20th century, but its slang incarnation postdates World War II in Philadelphia (05:54).

2. Yo-Yo’s Ancient Roots and Historical Development

• Yo-yos originated in the Philippines in the form we know now, but similar toys existed in Ancient Greece and possibly China more than 2,500 years ago (06:49–07:14).
• The yo-yo is considered the world’s oldest toy after the doll (07:26).
• Alternative historical names include lemigret, bandalore (British), and the quiz (08:27).
• Napoleon reportedly used a yo-yo for stress relief (09:07).

3. Evolution of Yo-Yo Design

• Early designs (Greek/Chinese/European) had a string tied tightly to the axle, leading to immediate return—no “sleep” possible (07:57–08:19).
• Filipino design innovation: string loosely looped around the axle, allowing the yo-yo to “sleep” (spin in place at the end of the string) (09:29–09:51).
• This innovation unlocked yo-yo tricks and modern playability.

4. The Birth of Modern Yo-Yos and the Duncan Era

• Pedro Flores, a Filipino immigrant, started the first U.S. yo-yo company in the 1920s; Donald Duncan later bought and popularized it (11:11–11:32).
• “Yo-yo” became a generic trademark in 1965, leading to the original Duncan company’s bankruptcy (12:06–12:23).
• At their manufacturing peak: “3600 yo-yos an hour… a million board feet of maple wood every year… sold 45 million yo-yos in 1962—more than the number of kids in the US!” (12:43; 12:52).
  • Chuck: “A chicken in every pot and a yo yo in every other hand.” (13:17)
• June 6th is National Yo-Yo Day (Donald Duncan’s birthday) (13:41–13:47).

5. Yo-Yo Physics: How It Works

• Linear Momentum: Classic up-and-down motion, as with the ancient/European model (17:24–17:45).
• Angular Momentum: Modern design allows spinning at the string’s end (“sleep”), key to tricks (17:46–18:16).
• Gyroscopic Stability: Keeps yo-yo balanced while spinning, resisting axis change (like a football or frisbee) (18:30–19:25).
  • Josh: “A spinning object will resist change to its axis of rotation.” (18:57)
• Waking Up: A tug increases friction, letting the yo-yo rewind up the string (20:11–20:23).
• Moment of Inertia: Designs distributing more mass away from the axis (“butterfly” yo-yos) sleep longer (21:34–23:00).
  • Chuck: “That allows things to sleep a lot longer. … One of the breakthroughs in yoyo design.” (23:00)

6. Modern Engineering Tweaks & Controversies

• Ball Bearing Axle: Allows even longer sleep times—controversially called out as “cheating” by the hosts (23:50–24:06; 25:01–25:47).
  • Chuck: “Let’s just call them modifications… for, sorry, kids who don’t know how to yo yo.” (24:05–24:09)
• YoYo With a Brain (Clutch System): Spins automatically returns when spinning slows, further distancing from classic technique (26:10–27:28).
  • Josh: “You could be in a vegetative state and do this yo-yo.” (26:15)
• Notable innovators: Tom Kuhn (No Jive 3-in-1 yoyo), Michael Caffrey (YoMega “Brain”) (27:51–28:15).

7. Yo-Yo Pop Culture and Trivia

• Abbie Hoffman: Used “walk the dog” yo-yo trick during his contempt of Congress hearing in 1968 (32:25–32:59).
• Richard Nixon: Famously (and ungracefully) yo-yoed at the Grand Ole Opry, 1974 (33:11–33:48).
• In Space: NASA tested yo-yos in microgravity (Toys in Space Project, 1985), finding they “move gracefully but never sleep” (33:54–34:24).

8. Yo-Yo in Education

• Teachers use yo-yos to explain angular momentum, gyroscopic stability, and moment of inertia in physics lessons (31:39–32:07).
  • Josh: “I have to tell you, I understand angular momentum far better now.” (31:57)

Notable Quotes & Memorable Moments

• On Yo-Yo’s True Purpose:
  • Chuck: “Sleep. That is why people yoyo. I think it is all about the tricks.” (09:51)
• On Modern Tweaks:
  • Josh: “Even as a kid… ball bearings and clutches… they just seem like cheating.” (10:04–10:13)
• On Design Innovations:
  • Josh: “The Filipino design led to the modern yoyo… The huge distinction is that the string is just looped around the axle kind of loosely, which has the added benefit of allowing the yoyo itself to spin once it reaches the end of the string.” (09:29–09:51)
• On Gyroscopic Stability:
  • Josh: “So if you have a yoyo that is sleeping and you push down on top… it’ll just keep spinning as long as it is spinning fast enough. Gyroscopic stability.” (18:30–18:57)
• On The Yo-Yo Space Mission:
  • Josh: “They found that, like, letting it drop did nothing because they were testing it in microgravity. But if you throw… it will still spin. And it moves kind of just… gracefully along the string… but it’ll never sleep.” (34:01–34:24)
• On Search Techniques:
  • Josh: “So you just put the minus sign.”
  • Chuck: “Minus and then the next letter. No space.”
  • Josh: “You literally just improved my life.” (35:40–35:52)

Segment Timestamps

• Intro/Banter: 02:41–03:40
• Origin/History of the Word & Toy: 04:08–13:47
• Physics Primer: 17:18–25:54
• Modern Developments and Tweaks: 25:59–28:28
• Trivia and Pop Culture: 32:24–34:56

Tone, Style, and Notable Dynamics

• Conversational, playful, and irreverent—Josh and Chuck riff on toys, history, and physics, with a sense of childlike wonder.
• Slightly nerdy affection for both traditional and modern yo-yo designs.
• Occasional skepticism toward “cheating” engineering advancements (e.g., ball bearings, clutches), favoring simplicity and skill.
• Offbeat pop culture tangents and a dose of SYSK nostalgia.

Brief Takeaway

This episode is a delightfully thorough and surprisingly nerdy journey into the world of yo-yos. It moves from ancient innovations to physics class, through legal drama and space missions—all spinning around a toy that’s simple, but “far out.” Whether you’re a yo-yo master, a physics teacher, or just a curious listener, you’ll leave knowing exactly how a yo-yo works (and maybe wanting to try a “walk the dog” yourself).