Methaqualone was manufactured in the United States under the name Quaalude by the pharmaceutical firms Rorer and "Lemmon" with the numbers 714 stamped on the tablet, so people often referred to Quaalude as 714s, "Lemmons", or "Lemmon 7s".
It was discovered that because the number 714 was also a slang term for Quaaludes, a prescription drug often used recreationally, young persons were stealing the highway signs.