Actually, we must ask:
Can anyone's, I mean any human's, ears be called tough?
If ears can be called tough, how does one measure that toughness?
You guessed it. By hanging heavy earrings on the ears that claim to be tough and checking the duration till the wearer can bear to carry those earrings. :D
Correction. Rather, an improvement in the measurement:
By hanging heavy earrings on the ears that claim to be tough and checking the duration till the ears can carry such earrings without getting torn.
This might sound frivolous but that's the way many women, especially those who are in the thrall of a major celebration, do in India.
Is it necessary to prove that one's ears (or ear-lobes) are tough?
Indian women would say, "We don't ask such questions, we just do it."