What is Teller of untruths, your trousers have combusted?

Is a phrase that has become popular after somebody posted on MLIA (mylifeisaverage.com) about translating the phrase "Liar, Liar, Pants on Fire!" to French and back again, and coming up with "Teller of untruths, your trousers have combusted"

Billy: Today I rode a Unicorn
Some Other Guy: Teller of untruths, your trousers have combusted

👍93 👎31

Teller of untruths, your trousers have combusted - video