How to use the Mixer Grumpycat Sticker on Discord
To upload and use Discord Stickers you need to have Discord Nitro and a server with at least 1 boost level. To upload and use the Sticker you need to go to the "server settings" page, under the tab called "stickers" you should see an option to upload a sticker. You should click the round plus button then select the image you just downloaded from this website.
stickers.gg