When someone is so wasted/drunk they are unable to speak properly, hence spelling "done" incorrectly.
"Man, after those shots at the party I was D - U - N"
D-Determination U-Unity N-Nutrition K-Knowledge A-Athleticism D-Defense E-Energy L-Leadership I-Intimidation C-Champion
The D-U-N-K-A-D-E-L-I-C is the blueprint to becoming a champion.