Caffeinis
Merging the words "caffeine" and "penis" - A disorder of male genitalia causing dicks to become aggressive and irritable, with tense muscles, difficulty sleeping, "vomiting", convulsions, and excessive alertness. Similar to symptoms of caffeine over usage in people.
I've banged my way through 3 different bars today, but my dick just won't go to sleep. I have a serious case of caffeinis going on here.