Fat people usually have cankles, but it can also occur with anyone.
(This is not to be confused with someone having thick ankles. If someone has thick ankles they still have a curve in their leg, but with cankles, the front view of their foot is completely straight.)
My boyfriend says I have cankles.
It is the condition where the ankle girth is equal to or indiscernibly less than the girth of the widest part of the calf. It is not ankle fat per se, but rather a state of being “big-boned” in the ankle region while simultaneously experiencing gross muscle atrophy of the gastrocnemius.
Symptoms include: deep elastic grooves from socks, increased razor wear-and-tear, ability to reap 20 bushels of grain per hour.
Man 2: "Hopefully she'll marry a farmer"