Direct link to where you can order one
It was called the Monster Cruiser (possibly the Coker Monster before that). For whatever reason, it didn’t sell as well as the unicycles and was dropped, while they continued to make unicycles! Possibly due to cost vs. price, and space required to manufacture and warehouse bikes vs. unicycles? That’s just a guess. The original Coker uni frames were clearly made in Taiwan (identical to low-cost main cap style frames of that era) so they may have been doing little or no in-house manufacturing beyond the tires. The later versions had more unique and brand-specific components, which may or may not have been manufactured in the USA.
Apparently Guy Hansen had a hand in that; something I’ve always wanted to follow up on, as a bit of unicycling history. They started making unicycles in 1998 (I think only available starting in '99; Gilby won one of the very first ones as a prize at the 1998 NAUCC) and it changed the world of long distance unicycle riding.
Yup. But in the case of 36" wheels, unicycles definitely played a role. If the Monster Cruiser had quietly died without a unicycle version living on afterward and spreading 36" tires around the world, that size may have faded away and not lived to see interest from the bicycling world for non-novelty bikes.
I was curious about whether Coker is still selling their unicycles. Looking at their website it appears that you can still order their Big One model, but getting to it is not obvious; you have to choose a tire type before you get to the linked page above, that allows you to order one. The Monster Cruiser and the V2 Unicycle can’t seem to be ordered from the site, though you can still place orders for accessories and parts.
Or not, since there are some obvious broken links on there, the cycles and parts may or may not still be available. 
I loved my original Coker (from 2002), and I also had a Big One model for a time, but sold it for too little money. I still have the V2 frame they sent me for testing and review. A cool unicycling oddity!
I was also fascinated to know that Ventana Bikes (the manufacturing facility for the Dirty Sixer) are made in Rancho Cordova, which is right in my local area. I used to ply the American River Bike Path through Rancho all the time on my Coker, and later my SilvaCycles KH Schlumpf 36.