We’ve checked with someone still in their 20s, and have been told that a “boombox” is a bit like a radio only mainly used for the playing of urban music in which the protagonists aggressively shout about buying a car that’s more expensive than their rival’s car over a repetitive loop of sound.
We hope that clears it all up for you.
It works, has a screen and controller ports, and would therefore let you play Dreamcast games anywhere there’s a plug socket. A bit like a… Dreamcast. Loads more photos of the Dreamcast-in-a-radio modification can be found here and there’s a literally appalling video of it in action here, if you’re as bored as we are of today already.