EBUCK
With the zucchini, it's usually a matter of everyone's over-planted the stuff in their garden, and they and everyone they know has all of it they want, so they start "giving it away". If you're not around to ask, you can't say "No.".
As far as the carp goes, all I can say is that snapping turtles have been known to find their way into unattended beer coolers left in the back of pickup trucks.