OK. You've seen my explanation for 'pop a cap in your ass.' In a sense what I was doing there was expressing my appreciation for the non-literal aspects of what might seem like 'low' language use. I wanted to point out that it is actually very clever, and, in its way, sophisticated. What slang would you make a case for being really clever? Make it sound like Shakespeare! Here's an 'off the top of my head' example: under glass - police slang for in jail. I like the 'small organism being scrutinized under a microscope' feel of that one. Synecdoche, glass for the whole jail which also has bars and concrete and so on.