Using Boost I don't know. But I use the markdown syntax, so I put an exclamation mark, then square brackets (any helpful alternative text goes there, in case the image won't load or for screen readers like for blind people), then the image URL goes into curved parentheses. It's super annoying to type it all out, but I love the gifs so...

And let's see if I can display the above in a code block...

![image](https://forumus-uploads-production.s3-us-west-2.amazonaws.com/original/3X/8/f/8fe49c77c0ecba566731bb9f269c7685d9a306a4.gif)

Yes! 🙌

Edit: now I will be curious what dark hells I have helped unleash in this, our darkest timeline.

With Boost, all you need to do is tap on the photo icon on the bottom line. Then you can add the GIF into the URL box. On top line just add any word you want.