While perusing manpages (col, specifically) I found that terminals respond to ^N by switching to an alternate character set (a drawing set, perhaps) while ^O will switch back to normal.

I often cat things I should not, and end up borking my terminal display, typing echo "^V^O" where ^V is CTRL+V and ^O is CTRL+O. This will echo ^O to your terminal and reset your character set.