A2A; I’ve already listed all I could recall under Nick Nicholas’ answer to What are the funniest nicknames you’ve been given over the years? For origins, see there.
- Nicko. Love (so Ocker!) Never used since 14.
- Acka Nicka. Hate. Never used since 15.
- Nick Squared. Like. Frequent use up to 17, very rare reinvention since.
- NSN. Indifferent (I don’t use the middle initial any more). 18–22. Is occasionally still used by people I studied with. (It’s a very computer geek thing: it was my email address.)
- The Minoan Genius. Love. Used once when I was 25.
- Opoudjis. Love. Used really only by me, since I was 25: it’s my self-chosen user name. (And I seem to be the only person who can spell it and pronounce it, anyway.)
- Niĉjo/.nitcion./nIchyon. Like. Esperanto, Lojban, Klingon versions of “Nick”, each drawn from its precedent. Niĉjo: used some when I was active (13–20). nitcion: used a lot when I was active. nIchyon: used a little when I was active.
Special mention, not mentioned in previous answer:
- Dr Nick. Love. Used when I was lecturing by my students (age 31), and intermittently since. Most recently revived by Tracey Bryan. To be delivered in Dr. Nick Riviera singsong.
Separated at birth.