Short for dictionary block, or urban dictionary block. The act of originating an urbandictionary entry before the true author can submit the word, thus stealing credit.
Dict-blocked also plays on the common phrase cock block
with "dict" being phonetically close to dick, a synonym for cock.
Andrew proudly invented beeroner while at the bar. Covertly, Patty dict-blocked Andrew by entering said word into Urbandicitonary.com from her blackberry.