well mine is kind of a funny story,

I used to frequently halo 1 and halo 2 land parties and blow them out of the water. I always used many grenades, and got very good at using them. so the name fraggy stuck (frag grenade).

The second part is that they called me faggy to make fun of me, so I turned my color pink. Just to kind of show them that i don't care. and now on halo 3 I made the pink unicorn clan, the name speaks for itself. I just find it funny when people try to make fun of my callsign.
(btw, i'm straight)

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"For the sake of historical truth I must verify that only the Greeks, of all the adversaries that confronted us, fought with bold courage and highest disregard of death." -Adolf Hitler (From speech he delivered to Reich on May 4, 1941)
^^^true story