Calling people by nicknames
Question
Why is it frowned upon to call people by nicknames
Answer
In many instances, referring to an individual by their nickname can be considered demeaning. Such an address may imply a level of intimacy that is inappropriate, especially when the individuals are not related.
There are instances where using a nickname is expressly prohibited, particularly when the nickname is offensive or degrading. It is believed that individuals who engage in giving degrading nicknames may face severe consequences, as indicated by the saying that they will never ascend from Gehinom.
Source
Bava Metzia
58b
‘All those who descend to Gehinom ascend from it except for three categories of people who descend and never ascend. Among them are those who give others degrading nicknames'.