a yimmy ghey is a fat blunt rolled with mid-grade or schwag marijuana, usually laced with other drugs or caffiene pills to heighten the effect, terminology popular in Wisconsin
"ghey" is an insult or used in place of "lame" or "suckish" or any number of similar words. it is used mostly because "gay" used to be an insult, but now being a more tolerable thing, "ghey" is it's own thing, not meaning to insult gay lesbian bi or trans-gender people, but to point out that something or someone is "lame" or "boring" or something of that sort.