Is it even called a GIF? I see these funny animated things that people post and I'd like to know how to do it. All I've figured out to do is copy and paste the link to the funny thing--but not how to post it so it just shows. How is it done?

How to add Gifs to your signature - Technical Help/Errors - Bigboibets Forum

Here is an example, I searched "gifs posted in your forum posts".

You post the gif on a photo sharing site, copy the link it gives you and paste it into your signature. Be aware that most forum sites have size limitations for avatars and signatures so ask or look through their rules. They may also have specific places for you to use when uploading photos and gifs, so asking for help in the specific site is recommended.