Let's not get confused here. Superbad and Knocked Up are "original" movies which, looking at the title, are subject of this spoof. I suppose another thread could ask if the likes of these movies are as good as their older counterparts. I just don't know if you can compare Porky's to the likes of American Pie, I think I may have just got old and the humour isn't as applicable to my life any more (when the likes of Porky's was released, I was about the same age as the characters, so life had exciting possibilities!
). Mind you, some saw Porky's as the new film and older foreign films, such as Lemon Popsicle, as being more the original.
Anyway, back to the original post (and remembering my statement about my age). Degsyhufc is spot-on with his comment about Airplane, Top Secret etc. Spoofs were very clever and very high quality in those days. Airplane II first introduced the concept of Bill Shatner having a sense of humour. The musical score of Top Secret was fabulous (I actually have it on vinyl somewhere in my garage) and Val Kilmer was fantastic as Nick Rivers. You could watch these films half a dozen times and still spot things you had not seen before, so much effort was put in.
I think some of the early Scary Movie ones were the last to be funny in any way. Meet The Spartans, Date Movie etc. have been truly poor.
Although any spoof is subject to you having an understanding of the original and may become dated due to references to news and culture at that time, it's still worth looking into the likes of Airplane and Top Secret.
