Social construct.

[Belacqua]

I've been reading through some threads on reddit in my spare time at work. At least I'm not the only one crazy enough to have had the thought everything might be a social construct because there's threads on there about it.

Oh, man, if you're doing philosophy on reddit you're a braver man than I am. It can get wild over there. 

Even some seemingly knowledgeable people on there were taking the question seriously. 
I don't know much about them but the concept is interesting.

Absolutely, I think it's a fascinating and important topic. 

Even if we agree that not everything (mountains, Pluto) is a social construct, I think it's true to say that how we perceive things is always filtered through our social construction of them. No one sees the world "raw," so to speak. Our socially-constructed images are always put in play to interpret and filter our perceptions. 

There's a saying in art school: "Seeing is forgetting the name of the thing you see." Because the ideal, for some artists, is to draw what's there as directly as possible, without accepting influence from our social interpretations, our selfish desires for one thing over another, etc. Nearly all beginning artists, for example, draw the faces much bigger in proportion to the body than they really are, just because the faces are more interesting to us. (And if the model is a woman, the guys draw the boobs too big.) This is maybe not exactly what "social construct" means, but it certainly parallels the idea that what we perceive of the world is strongly adjusted by our ideas about it.

Recently among people who study aesthetics the big topic has been "The Aesthetics of Nature." The thinking behind this is that we have been trained to look at the world as if it were a work of art. If we look at the view from a train window and say, "Oh, that's beautiful," usually what we mean is "Oh, that looks like a painting." So these modern guys want to dissociate our judgement of beauty and interest in nature from our judgement of beauty and interest in art. Art being very much a social construct, they want to discard that as a criteria for judging non-art things. I'm not sure it's quite possible, or what will come of it. But it's evidence that, as you say, teasing out the social constructs that we inevitably use in perceiving the world is a worthwhile thing to do.