The firearm or plastic gun seems to be having this movable arm where the whiskey glass is supposed to be held. The schematics also seem to be confusing since it is also possible that the glass can be flipped when operating the gun. In terms of obviousness, the invention does seem unique in that no everyday person would dream of coming up with this contraption. Also, the device does not seem really novel since it is fairly easy to just attach a mount on a gun.
Also, the invention does not seem useful since it ends up encouraging the behavior of drinking with operating guns. As statistics have shown that people that text and drive do not perform well, the operation of a gun while having access to whiskey can only lead to unintended consequences potentially. In light of recent events, this invention would probably meet a lot of social opposition as well.
Some people may argue that the invention is intended for plastic guns which are harmless. However, plastic guns are often considered to be toys which kids often use so I am sure such a device would not be popular to have kids with alcohol. Overall, the invention may have been more useful if it was a scope or helped focus the aim or even a safety lock.
http://blog.edisonnation.com/2009/08/did-you-know/
http://www.freepatentsonline.com/3450403.pdf
http://www.google.com/patents/US3450403