What are your favorite nicknames that you heard of or gave to specific anime characters? Here are mine:
Nanoha - "Demonic Cannon Girl" (From the series Mahou Shoujo Lyrical Nanoha. Pun on mahou shoujo, where mahou = magic, shoujo = girl or ma = demon, hou = cannon, shoujo = girl. I think this name fits as Nanoha has such a proficiency at blowing things up that she would put humongous mechas to shame.)
Gundam Exia - "Termin-exia" (From the scene in an episode of Gundam 00 season 2 where you see a broken Exia with its glowing red eye)
Kira Yamato - "Jesus Yamato" (For his god-like status given to him in Gundam SEED Destiny) and "Aimbot McBeamSpam" (for his excescive use of his Gundam's auto-aiming system to spam his nuclear-powered weapons as much as he wants)