Lay's is a brand of potato chips, as well as the name of the company that founded the brand in the United States.
The brand has also sometimes been referred to as Frito-Lay because both Lay’s and Fritos are brands sold by the Frito-Lay company, which has been a wholly-owned subsidiary of PepsiCo since 1965.
The famous slogan appeared in a commercial called “Messier, Just One” from Lays 60 years ago.
"Betcha can’t eat just one” was the 1963 advertising campaign slogan by Young & Rubicam.
From then on, this slogan became well-known and people tended to think of Lay’s when they saw or heard anything about “Bet you can’t eat just one”.