Step 1:

Get yourself next to a wall. Any wall that you're head can touch.

Step 2:

Get as close to the wall as possible, leaving room in front of you. Pause the game by double-pressing the equip button. Move forward and unpause.

You should now be heading in the opposite direction of the wall at super speed.

This likely works because of the method in which the game prevents you from going through walls, we can easily exploit this by going in to a wall while the game is paused, then unpausing.

The game thinks you're in the wall, so it pushes you out of it, however the game seems to just give you speed in the opposite direction, depending on how far in the wall you are, with seemingly no limit.

Whether or not the same technique can be used to get through thin walls, I haven't tested yet, but I'll upgrade this guide if I can find a way to do so.