Abbreviation for "dick in your mouth". Sometimes used as a quick way of smiting your enemies. Has other incarnations such as dimm - dick in my mouth, diya - dick in your ass, etc etc.
Came into use in an IRC chat room and quickly took off from there.
This abbreveation for "Dick in your mouth", is also used as a word to replace damn in sentences to people you have no respect for, but maintaining it's "dick in ya mouth" meaning.
Contrary to the chat room deffinition, this term was developed by a friend and myself over fifteen years ago, as a way to fuck with a guy at work who we had named "Dicknyamouf". Example. "Hey dicknyamouf, bring me a soda!"
some dumptruck at a bar won't quit yapping her hussy face off; rather than insulting her and her friends or trying to continue to just get laid, wait for an obnoxious laugh and pop your entire finger into her mouth while saying "dick in your mouth! DIYM". conversation satisfyingly over, and at least you get a good laugh out of it.
girl was giving me head during Boondocks and the line fell "nigga you better have insurance, KNYICKAH YOU BETTER HAVE INSURANCE, /ASSWHOOPIN INSURANCE" and we both died laughing, her with my dick in her mouth.. hince, diyml!