Kind doesn't mean let everyone walk all over you. It's possible to kindly tell someone to fuck off. I've even seen people use those exact words and still appear kind.

Edit: Mildly interesting. 50 minutes after this comment, I was searching for how to calculate the intersection points of collinear line segments which brought me to Stackoverflow [1]; where someone linked to this sketch [2] about drawing red lines with green ink, all perpendicular; which then brought me to this sketch [3] involving politely telling someone to fuck off.

[1] https://stackoverflow.com/questions/24511962/calculate-inter...

[2] https://www.youtube.com/watch?v=BKorP55Aqvg

[3] https://youtu.be/sxCWB47ZCLQ?t=1m53s

I still don't know how to calculate the intersection points of collinear line segments.

This guy delivers the goods