Piranha 3D
Yeah, so, this shit is fucking mental. I was talking to a mate about it on MSN and he actually said 'You are making this shit up'. If that's a recommendation then I don't know what is. This is a bold, silly, sexy, gory movie and every time you think that it can't get any more ridiculous - it manages to one up itself (so obviously it comes as no surprise that Eli Roth makes a cameo appearance).
Also there's an underwater lesbian sex scene and particularly hilarious turns by Christopher Lloyd as someone who is essentially Doc Brown and Ving Rhames as a cop who single handedly takes the fight to the piranhas with an outboard motor.
I mean, there's no way I can call this an objectively good movie. But that doesn't mean I didn't enjoy the hell out of watching it.