See this GIF? Too large. So I copied it from another post that I'd written, pasted it, and boom. If you can get to someplace where you can copy and paste the image, you're set.
Try that site. Load an image, use your mouse to capture the picture, hit command+c, or whatever it is on a PC, and then command+v.
Yuuuup. Used this Quill GIF on lunapic, uploaded it from my computer to the site, then copied and pasted it in.