One of the key traits of my homebrew chapter is that they're fighter pilots, so whenever one of my character models fails in a memorable manner, if he doesn't have one already, he's getting a callsign (and a name if I haven't named him by then).
Currently i have:
- Techmarine Takao Mataumoto, callsign "anvil", because he got beat up by a Salamander. Said Salamander was a sergeant--not even a character model, but just a regular guy.
- Captain Imai Kichiro, callsign "Grotslayer". In a battle against the Orks, a grot sniped him in one hit (including a CP reroll for the saving throw) while the rest of the squad remained unharmed from the rest of the unit's shooting.