Not just because everybody else gets one of a butterfly, but because they have a very special meaning behind them.
Butterflies start out as caterpillars. And no matter what's happened to the caterpillar in the past, it can always choose to hide away in it's cocoon. And when it's ready, no matter how ugly the caterpillars once were, they emerge into these beautiful creatures that can fly away into the sky and forget about everything they once knew. They are free. However they are still incredibly delicate creatures. If their wings are touched even once, they may never be able to fly again. They are delicate, and remain so their entire lives.
Butterflies hold special meaning to me, and I very much am trying to find a good tattoo. A really beautiful, perfect one. One that looks like my description of a butterfly, beautiful, free, and delicate. Graceful. Calm.