Bog (1983) 
Bog is one of those films that makes you wonder whether the film-makers were intentionally trying to make something bad for comedic effect, or whether it was just something that looked better in their minds / on paper than it did when translated to the big (or small) screen.
The overall plot concerns a blood-draining prehistoric swamp monster who is awakened one day by a hapless fisherman using dynamite to win his catch.
After the dynamite fisherman comes to an abrupt end, the rest of the film is bulked out by two couples who are sauntering through that part of the swamp, vacationing together. The four seem to have been kidnapped from an entirely different film as their mundane bantering plays out almost like a dull comedy skit without any punchlines. After the two wives fall prey to the swamp beast, the husbands join the ramshackle police investigation and do not seem to be too upset about their wives' demise, which whilst understandable from this viewer's perspective just enhances the fake, two-dimensional characters and unbelievable nature of the film even more.
Fake and tacky seems to be Bog's specialty, as when the monster is revealed out of water to be nothing more than a man with a cheap rubber suit and rag ensemble waving his arms around you can't help but stifle a laugh... However, due to the overall ineptitude of the proceedings, I'd all but given up caring by that point anyway.