When Cousin Jimmy brings his new girlfriend and her three kids without telling you, you're gonna need a bigger table. If you're handy (and we know you are), that's an easy problem to solve.
To construct a makeshift, temporary table extension, rip a sheet of ¾-inch plywood to the width of the table. (For extra strength, rip two sheets and double them up.) Cut the plywood to the desired length, and also cut three 2x4s to this same length. Set two sawhorses off the end of the table (parallel to the end), and lay the 2x4s across them. Screw the 2x4s to the sawhorses with 2 ¼-inch deck screws. Lay the plywood over the 2x4s and fasten it down with 1 ½-inch screws. Cover it with a tablecloth, and no one will be the wiser.
Don't have any plywood? Take a flat-faced closet door off its hinges, remove the knob, and lay it on the sawhorses. Just don't screw it down.
Last-minute shopping item: Deck screws