Lisa, I want to buy your rock!

This is one of the best examples of the Post Hoc fallacy out there. For a long time, a clip of this was unavailable on the internet (I don't know why), but today I finally came across one, and here it is:


The key here is Homer's confusion about the rock. If we reconstruct his argument it goes like this:

1. Lisa has a rock.
2. There are no tigers.
3. Therefore, the rock kept the tigers away.

It is the assumption that the rock caused the tigers to stay away which is the Post Hoc fallacy.