Saw a model today for something I never knew existed & it seems like something straight out of All Time Wacky Weapons; A WW2 German Mobil MG Bunker or "Panzernest!" This is a steel cubical that is towed into position on 2 spoked wheels. I would guess it's probably 7 feet tall, with wheels, & probably between 5-6 feet wide. My first impression, from the photo on the box was this was towed into place, propped up on a log & left, which was absurd enough! However, it is worse than that! Thanks to schematic drawings on the box, you get to see how this weapon is actually used. Apparently, you, somehow, tip this thing upside down, remove the wheels & tow bar(because that's where the gun port is!). It appears to be enclosed so it's like shooting out of a tin can! OUCH! Since the MG does not stick out thru the hole, it looks like you shoot straight ahead or not at all, tho there does appear to be fixtures to traverse & raise the barrel. It has an air pipe & periscope. This is one of the craziest things I've ever seen! Look for yourself;
http://www.ebay.com/itm/A-C-E-1-72-scale-WW2-German-MG-Bunker-Panzernest-Model-Kit-A-/131728476718?hash=item1eaba10a2e:g:~AoAAOSwuAVWwcjbhttp://www.ebay.com/itm/A-C-E-1-72-scale-WW2-German-MG-Bunker-Panzernest-Model-Kit-A-/131728476718?hash=item1eaba10a2e:g:~AoAAOSwuAVWwcjb

I think one of the best wacky weapons of WW2 is the bouncing bomb:

Actual Bouncing Bomb Movie

I've seen something similar and, perhaps, a little whackier that was used by the British Home Guard at a time when there was a real fear of invasion, and much of the British Army's equipment had been lost at Dunkirk.

A semi cylinder with two large wheels, the tow bar was a gun barrel. After being wheeled into place the device was flipped on it's side so that it traversed on the wheel it was sitting on. Potentially more dangerous to the user than the target, desperate measures for desperate times. It seems the comic antics of "Dad's Army" are a little more real and more serious than I thought.

http://www.ww2incolor.com/homefront/SmithGun.html

Portable bunkers like this were intended to quickly supplement static defences with hard points and would most likely have been dugin so only a small part would be visible, and have mostly been around since at least the 19th century so considerably before WW2, this version is just another spin on the concept originally I believe started by Gruson in the 1880s...

http://www.lonesentry.com/articles/mobilepillbox/index.html

Colt .45 pistol as a fully automatic version. Some were carried by aircrew in the USAAF in WWII.

http://www.thefirearmblog.com/blog/2010/03/29/colt-m1911-machine-pistols/

Mike Bunkermeister Creek
Bunker Talk blog