Liquid,
I think Hacker raises some good points. By posting numerous, random, bandwidth intensive posts with direct links to off-site image files, you are spending the resource of someone who has been generous enough to provide this service for MobileRead visitors and members. By doing so, you're being a bit inconsiderate. While you may find these items funny and want to share them to "help people by making them laugh", you are doing so at the expense of someone else. Like Hacker said, inserting images directly from another website (and without citing the source) is inappropriate and is not proper web etiquette.
If you'd like to create your own site with collections of random items you come across, there are several free personal blog services like
www.blogger.com where those type of posts are more appropriate.