I took the Twitch userbox from Template:User_Twitch and changed the design.

You can choose to either have your Twitch profile linked or not.

Usage

edit
Result Code
 This user watches or broadcasts on Twitch.
{{User:Nulcheck/ubx/Twitch}}
 This user watches or broadcasts on Twitch as Nulcheck.
{{User:Nulcheck/ubx/Twitch|Nulcheck}}