Here is how you paste the gif in.

I would do this. If you want that gif in your sigline, then I would first of all click on the link you put here in your reply and have it open the gif in a separate tab. Then I would go to My JPR and open your profile setting it to edit your profile. I would then go back over to the gif and right click it and tell my computer to save it to your clipboard. Go back to the profile edit area and paste it into your sigline.

Should do just what I did right here. You can even size it if you click on it in the sigline while it is being edited. The gif will be bracketed and you can drag any corner in or out and make it bigger or smaller.