A DP-UH is an abbreviation of a gun from popular shooter-looter game Borderlands 2, it stands for Double Penetrating Unkempt Harold which is a play on words for a dirty harry. This term is used by popular Borderlands Youtuber Obeshoesgames.
Guy 1: What gun do you get from savage lee in Borderlands 2?
Guy 2: It's a DP-UH Bro.