The most irritating acting I've ever witnessed

Just because you are "trying" to make a spoof / comedy horror does not mean you should be acting as if you are in a child's pantomime.

No matter how ridiculous or 'comical' the plot - your actors still need to come from a place of TRUTH and therefore believability rather than moronic slapstick that is typical of too many Aussie attempts at comedies.

The plot and the script / dialogue should be good enough that your actors don't need to ham things up to the point of insanity. They should truthfully deliver what is given to them and if it's quality, it will work. Compare this type of crap to any decent comedy/horror (whether low budget or high budget) and notice the difference in what the actor's are or are not doing. It might still be slapsticky - but it won't be absurd and untruthful.

If we don't BELIEVE what the actor's are saying and doing, it is usually impossible to be taken in by the story. Save the clowning around for the circus.