What's weird about US/Canada? I thought it was pretty straightforward. Was this about the "Angle" on Lake of the Woods?
The border is defined as a straight line, but was surveyed as a series of slightly wobbly series of lines. They put up thousands of stone pillars, cut out a strip of trees along the border, and it became official.
IIRC there's also some stuff about a disputed island
I heard that kids there go to school in Blaine, which means 4 international border crossings every day!
https://youtu.be/SxhUsPBFPkU?t=1m46s (Geography Now! Canada - btw awesome channel for people who like geography)