A combination of the words "thigh" and "ankle". A variation of cankles, thankles are the non-definite ending of the thigh and beginning of the ankle. Most common in fat guinea pigs.
He is so fat and orange, he has like a triple chin. He has thankles.
An exaggeration of 'cankle'. Whereas 'cankle' is a contraction of 'calf-ankle', 'thankle' is 'thigh-ankle'. Indicates that there isn't just no discernable ankle, but no knee either.
Speaker 1. Sally has such cankles.
Speaker 2. No, they're not just cankles, they're THANKLES!