Guinea Pig — Meaning, Idiom & Expression Origin

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Candace Osmond

Candace Osmond studied Advanced Writing & Editing Essentials at MHC. She’s been an International and USA TODAY Bestselling Author for over a decade. And she’s worked as an Editor for several mid-sized publications. Candace has a keen eye for content editing and a high degree of expertise in Fiction.

Being called a guinea pig means you’re a test subject, someone who’s diving headfirst into trying something new, whether by your own choice or by the force of others. Want to hear the story of how this tiny rodent made its way into our conversational vocabulary? Well, I’ll jump into the hay pile of this idiom, explain where it came from, and show you how to use it.

Guinea Pig Meaning as an Idiom

Guinea Pig — Meaning Idiom Expression Origin

In the idiomatic world, when someone says you’re their guinea pig, it’s not a comment on your dietary habits or cuteness. They just mean you’re a test subject, trying out a new process, product, or idea before it’s rolled out on a bigger scale. Think of it as being the first to dip your toes into uncharted waters, or in this case, the first to nibble at a new piece of lettuce.

It’s like when I found an overseas printer for my special edition books. I was terrified about dealing with a company outside my country, worried about potential issues, etc. But an author friend of mine was already in the process of ordering from them, so I let her be the guinea pig and test them out for me! (Good thing because they turned out to be a horrible printer!)

Is Calling Someone a Guinea Pig Slang?

It’s not so much slang as it is a popular idiom. Guinea pig literally refers to the cute rodent, but using it to describe someone as a test subject is an established and widely understood idiomatic expression. So, it’s a step above casual slang and has earned its spot in standard English.

Origin and Etymology of the Guinea Pig Expression

Guinea Pig Ngram
Guinea pig usage trend.

Even though rats and mice are way cheaper to use in scientific experiments, guinea pigs were also utilized. Some say it was because of their mild nature and ease of handling. This practice goes back as far as the 18th century when the Navy used the term to describe green sailors, aka inexperienced ones.

It’s hard to say which came first, the Navy or the scientists. But one thing’s for sure, this idiom originates from the idea of using people to test out products and theories.

Guinea Pig Synonyms

  • Test subject
  • Lab rat
  • Proband
  • Experimental subject
  • Test case

Guinea Pig Idiom Examples in a Sentence

Guinea Pig — Meaning Idiom Expression Origin 1

  • Jake was the guinea pig for the new virtual reality game, and he loved it!
  • “If you’re looking for a guinea pig for that spicy taco recipe, count me in,” said Clara eagerly.
  • The teacher used me as a guinea pig for the new teaching method; let’s hope it’s effective!
  • Before launching the new sleep app, the tech company needed a few guinea pigs to test its user-friendliness.
  • “I’m not your guinea pig!” exclaimed Ben when his sister tried out her new hair-dying skills on him.
  • Every innovative product starts with a brave guinea pig ready to take risks.
  • During the trial phase of the medication, tons of volunteers played the role of guinea pigs.
  • The latest fitness trend was intense, but Megan was up for being the guinea pig.
  • To make sure the drink wasn’t too strong, Josh acted as the guinea pig and tasted it first.
  • “I’ve never tried this cake flavor before, so consider yourself my guinea pigs,” said the chef with a wink.

Are You a Guinea Pig?

If someone ever calls you a guinea pig, make sure you know what they’re testing on you! Hopefully, it’s just a new, delicious dish they cooked up and not some experimental procedure. Add this idiom to your arsenal, along with all the other ones I break down right here on our site!