You understand that there’s a difference between “calling yourself” and “giving yourself” a nickname? The latter wasn’t stated by me, so I don’t know why you’re bringing it up.
If your buddies called you killer, and you used it, that’s calling yourself the nickname. Of course it’s lame to give yourself one. But when you get introduced to people, using the nickname they would use is okay. You’re just spreading what’s already been given to you.
Calling anyone green shit, even as a joke is just being a shit person, don’t need to extrapolate anything when you’ve laid it bare.
I’m not a nuclear guy or anything, but suit and containment unit? Seems unnecessary and would make the hands very unwieldy through 2 pairs of gloves.