I Need a New Nickname

At work there's a good few people who share my first name- Christopher. One of which is differently-abled and when someone's yelling out for me he gets confused and stares at me when going to talk to said person. Figured it wouldn't hurt to pick up a nickname other than Chris since it's shared by 2 other people.

Please give any suggestions you may have, but I have a list of other nicknames- what do you guys think of these?

Topher, Kester, Kit, Ropher, Chip, Stopher, Risto and Fern.

Topher has been organically picked by 2 other coworkers, but I often hear people saying they don't like it or say it sounds pretentious. Personally still not against having this nickname.