Many other insults are related to, and possibly derived from, this one, for instance, shitface, shithead, craphead, dunghead, shitbrain, etc. All of these words share the common structure "word for faeces" + "word for part of head". There is also a more general category of words which have the structure "some kind of vaguely insulting substance" + "body part", e.g. "cheese-dick", "strawberry-dick" (note that hyphenation varies with these types of word, although you will rarely see "poo-face").
A word which is related to pooface is rondabe, which is often discovered by accident when someone is writing a predictive text and tries to type "pooface". For some reason, many predictive text systems prefer the word "rondabe" over "pooface". No-one knows why this is, however. Incidentally, rondabe is the absolute certified coolest word in the world, by a margin of 58%. The nearest contender to its crown of coolness is globule, which has only 538 coolness points, and was used by Queen Elizabeth II in the Queen's Speech of 2002 in order to highlight her coolness.
Why are you straining, is that your poo face?