I think I found the ultimate G.O.O.D lap gun

My wrist ached when I looked at it.

 

The Serbu Super Shorty is a fun little gun, but not really useful for much other than something like a "lap gun" as the OP mentioned, or something to show off to your friends. They have a (relatively) small ammunition capacity, a very short CYL bore barrel with most loads spreading very quickly (making the gun ineffective much beyond about 5-yards) and no stock (can't put a stock on an AOW) giving you little control or ability for more precise shots (again, back to the close range application). With the Federal LE 00 Buck loads with their Flightcontrol wad I've gotten some very good groups with the little Serbu (all nine pellets into just a tick over seven inches at 20-yards). Just about every other load spreads like a disease though. They're not very expensive, but with all the hoops one has to jump through for such a novelty, I don't see it being worth it and would try to dissuade someone from buying one if they were looking for anything with even just a smidge of practically. Heck, for the money spent on one little Serbu a guy could have a couple normal 500/590s or 870s and some ammo to practice with. If you have to have a class three shotgun I believe an 870 or 590 SBS is the way to go (can have a stock and can get the Remington with a MOD choked barrel) Tax is $195 more though.