From the Wiki article > Richard Stallman summarised the difference in a slogan: "Think free as in free speech, not free beer." Free as in lunch would also wor

From the Wiki article > Richard Stallman summarised the difference in a slogan: "Think free as in free speech, not free beer." Free as in lunch would also work, but I'd hazard to guess that "free beer" is more relatable for the target audience Stallman was addressing. That being - computer enthusiasts ("nerds") who skew(ed) largely male, 16 - 35 (roughly).