explain yourself / keep it simple / elucidate
Malcolm X would say "Make it plain" prior to being introduced. He did not want you to add a lot of fluff or "yeast it"
Long-held black American church tradition. When the preacher delivers an inspiring or compelling message, the congregation often says "Make it plain"
Then the LORD replied: "Write down the revelation and make it plain on tablets so that a herald may run with it. Habakkuk 2:2
Note that the legal definition of "in possession" can at times include "under influence;" for example, the Michigan MIP law allows for a legally drunk minor to be charged with possession. This amendment was intended to close a loophole related to drinking in Canada; in previous cases, defendants had argued that drinking in Canada did not constitute possession in Michigan.