11. Middle finger.
Natsu was hardly ever vulgar. Apparently in all that time with the dragon, Igneel had decided not to expand the boy's vocabulary to the coarse. Lucy imagined anyone who lived as long as a dragon had to have picked up a few insults here and there.
But even in his fights with Gray, Natsu's insults hardly went beyond "droopy eyes" or "underpants man". Lucy may have been brought up as a Lady, but even she could do better than that. She was very well read after all.
But as she sat comfortably on a log with Happy, watching Natsu trounce the group of highway-men they'd been commissioned to deal with, she supposed he didn't have to be.
After all, for his opponents, the sight of the pink-haired boy walking away completely unscathed and high-fiving a small blue cat must be much worse than any insult, gesture or insinuation she could think of.