For the most part, galaxies aren't dangerous. In fact, there have been numerous collisions between the Milky Way and other dwarf galaxies, and it doesn’t impact us in any way.
A major galactic collision between the Milky Way and Andromeda is predicted in about 5 billion years, and even that wouldn’t have too much effect on the solar system. Luckily (or unluckily, depending on how you look at it), we won’t be around to deal with possible consequences, as the Earth’s surface will have become too hot for liquid water, and all life as we currently know it will have expired. Cheery thought, I know.
But, as minor as galactic collisions have been in recent history, the proximity of galaxies isn’t completely asymptomatic.
If a nearby galaxy passes too close to Earth, it can disturb the atmosphere. When this happens, meteors burn up faster than average. And if the meteor burns up quickly enough, it becomes a shooting star.