>>99642268When the character has a non-standar body type, aparently.
I mean all these girls are the same default, ground-zero stick figure so you can only go up from there.
Thiccness is also commonly asociated with non-skinniness , so to better convey this quality some people indulge in some degree of what could be considered fattness or even chubbyness. Your mileage may vary here.
As a rule of thumb, a prominent hourglass figure or just a pear one should suffice i guess