It's my first time to post here at the GFX section. I know a website where you guys can resize your .gif images in fastest and easy way without using any tools.
Here: http://ezgif.com/resize
If you already have a .gif format image, then upload it right there then do some configurations like resizing, etc.
But if you don't have and maybe for those who's using their iPads or iPhones (I know you can't save a .gif files on IOS), visit: www.giphy.com for more cool .gifs!
Copy the .gif's url then paste it to that site (http://ezgif.com/resize) and just like what I said, do some configuration.
*Best way for those who wants to change their signs here without a hassle
Hope this helps!