This is a bit of Thrilling Adventure Hour in-joke. You see, the one character, Sparks Nevada, who is the marshal on Mars, has a pair of robot fists. Which he uses to dispense justice on the red planet. Naturally.
So, TAH had a 9th anniversary show earlier this year (happy birthday, guys!) which I went to, and every time the robot fists were mentioned, the audience loudly and enthusiastically yelled "POW!" Naturally.
Anyway, I got this idea into my head and this is the result. A piece of fan art really. But the really cool thing? They're selling this design now as a t-shirt at the live shows! Right now it's a merch table exclusive, but if you're attending the show at Largo in Los Angeles, you too can get your very own POW! shirt. I got mine (signed by the cast and creators!) as you can see.
The Thrilling Adventure Hour is a live show (recorded for a weekly podcast) in the style of old time radio, performed at the Largo theater in West Hollywood. They take the show on the road from time to time and I have been fortunate enough to become involved in creating promotional material for these away shows.