Horror comedy is a hard trick to pull off. For a good example, consider the very short web animated series Llamas with Hats.
Each episode is very short (circa 1:20) and very simple. One llama asks the other llama about what hes been up to. The results are pithy, almost entirely dialog-driven, and increasingly horrific.
Try the first one for starters:
(thanks to Steven "Not responsible for the meat dragon" Kaye)