If we were to colide with a galaxy tommorow hopefully a giant landmass flies close enough to the earth that first we experience weightlessness before the earth's gravity is overcome and we all fall into the sky before we burn/freeze/get squished. Unfortunately people on the opposite side of the earth will just experience more and more gravity. However a select group of people on the side of the earth might get to experience falling sideways

Or the two spiral galaxies merge into a giant rasengan