This mug is already full...
Of great Sonic detail, that is! It is completely covered in Green Hill Zone themed design both on the outside, and the handle, but also on the entire interior too! Then, when the drink is finished, there's a special surprise design of a star bumper at the bottom. 

It is done in the 16 bit pixelated style, with jumping Sonic sprite on one side, among sunflowers, palm trees, rings and clouds. Notice the palm tree is on the handle as well. The inside appears to just have palms, but it seems to be difficult to photograph. This is a larger than normal mug, at 20 ounces of liquid. It is a Spencers' Gifts item in summer 2017, & should be sold both in stores and online.