There's an observed anisotropy in the cosmic background radiation—it doesn't seem to be totally homogenous, but rather there's a slight discrepancy in one of half of the sky compared to the other. The plane which cuts the sky into two "halves" is nearly perfectly aligned with the plane in which bodies in our Solar System orbit. This is a challenge to the Copernican principle that our Earth does not sit in any particularly privileged place within the universe—in fact, it's such an affront that cosmologists have named it the "Axis of Evil".
Struggling to explain this finding, they were simply hoping it would "just go away", but as the data amasses they're finding that it's here to stay.
Moreover, this has led to other unusual observations, like that, for example, that galaxies in the universe, which previously seemed to be scattered randomly, have a greater-than-expected chance of actually being aligned with this axis.
Of course, if you bring this up on Reddit, you're bound to get a lot of "It's probably just observational error, dude", and "No way, there's nothing special about Earth's situation in the universe. Just trust me, it's science" and so on. And in fact, scientists themselves are desperately trying to explain it away like that. But it's just one of those things that won't go away no matter how much we wish it would, and as the evidence mounts up, it seems more and more likely to stay.