Personally, I love the posts on favourite quotes/cartoons/jokes. They are some of my favourite posts to read on this site. It would be a real shame if they were closed, since it is good to allow more answers from new users. Closing the questions locks them up and it makes new users unable to share their own answers on the questions, which I think is a shame.
If this kind of question becomes a genuine problem with people complaining that these are out-of-scope (e.g., to argue that their question should be allowed in) then I would recommend adding a new category explicitly to keep these questions on the site, but make acceptance conditional on moderator discretion:
This tag is used for posts that solicit amusing or pithy material relating to statistical theory and practice (e.g., cartoons, jokes, quotations, stories, etc.). This category is created to allow a limited number of amusing posts beloved by the CV.SE community, that would otherwise by out-of-scope on this site.
Warning: Posts under this category will be closed by the moderators unless they are unique non-duplicated posts, and show immediate and lasting popularity on the site, as evidenced by high numbers of up-votes from CV.SE users.