Another New Body Hack?

Today somebody lent me a so-called Bulgarian bag. It's 27 lbs and homemade - a tire tube filled with sand and rubber mulch, ducktaped shut. (The name brand online this size is $175!)

I haven't tried it out yet but will do so soon. I guess it's supposed to be another Communist-Bloc *ab ripper* a la kettlebells.

I'll try anything other than crunches and running!