Hypothesis #4: Sanji twists antennae into his eyebrows.

On the beach, Sanji wiggled his bare feet, relaxing beside a girl he knew. They talked about what they liked, and disliked, and just... chilled... before Aja said the crucial thing.

"You know that guy? Fraches? With the curls in his hair? Even his eyebrows have a few kinks! He's so hott!" She was drooling as she spoke.

"..." Sanji fingered his painfully straight eyebrows in silence. Until he had an idea.

Without saying goodbye, he ran into the woods and caught a caterpillar. He mercilessly killed it and removed its antennae, which he curled into his eyebrows carefully.

"Now I'm hott!" He whistled in contentment as he returned to the beach. No matter how old he got, once a week he would be sure to catch new antennae.

END.