This mug is shaped like the barrel of Trioxin gas in the film, Return of the Living Dead (1985), that contains the zombie known as "Tarman". You can see Tarman through the "window" in the top lid.

From Ohana Is Dead:

"A crack in the barrel has released 2-4-5 Trioxin gas and reawakened the zombie!

Enjoy your favorite drink in this massive barrel mug featuring the corpse of a cult classic! Be careful, though...too many drinks out of this 40ish ounce mug could turn you into a 2-4-5 triombie.

Handmade by our good friend Munktiki in Astoria, OR, our Send More Paramedics! Barrel mug is limited to 25 total mugs."