DOADD is an acronym for Delayed Onset of Attention Deficit Disorder. Soon after ingesting too much caffeine, one may be so wired that he feels like he has a temporary case of ADD/ADHD.
It is a play off of the medical term DOMS, which is the muscle soreness one feels after a hard workout.
"Dude, I drank way too much coffee this morning. I can feel DOADD coming on!"