This stands for "There ain't no such thing as a free lunch!" Something doesn't come from nothing is what this says. This has to do with thermodynamics somehow.Common expressions often use acronyms, the first letter of each word in a phrase. All workers know TGIF means thank goodness it's Friday. The email and texting have made acronyms even more popular, such as OMG for Oh my God! or LOL for Laugh Out Loud, etc. Reading English requires an extensive knowledge of vernacular language. We don't usually use acronyms when writing, except very informally. Best English usage is to explain acronyms the first time they are used. Subsequent uses don't require explanation. Insiders use acronyms as a short-cut that unintentionally excludes outsiders who are not familiar with the jargon of a particular field. Most of my tutoring students ask for help with the myriad expressions, idioms, and abbreviations of everyday English.