to go against the grain= to do something that is the opposite of what is usually done. Examples: It's not easy to go against the grain and buy stocks when others are selling them. The changes in management will certainly go against the grain here. Etymology: from the act of cutting wood against the grain (in the direction opposite to the direction in which the fibers in the wood lie)

and here's the band singer explaining the expression for an english learning audience, making a reference to fish swimming upstream instead of downstream and a little sidestep to punk music :-) http://youtu.be/JaD0QR8zgZ4

to answer with a song, here's "Against the grain" from the band Bad Religion: http://youtu.be/GvmcJZ5r1o0

When you look at a piece of wood, you'll see the pattern goes in one direction. This is called "the grain" of the wood. It's easy to cut and sand in this direction (with the grain), but messy and difficult to go the other way (against the grain). We use this meaning figuratively, when someone does something opposite or contrary to what is considered normal or acceptable in that situation.

It means to do something that is different or against what everyone else is doing.