Oh noes! I've been undone by the taking the p:ss out of my use of the "..." punctuation again! That sure showed me.
To answer the question of why it make you look like a d:ck it is because:
1) People that put a y on the end of their friends names are generally d:cks. Unimaginative and all that.
2) They are not your friends.
Now if you would care to explain why you're doing it then and there are good reasons then perhaps it's not the actions of a d:ck. But it would appear that you think that (and you're by no means the only one) that by giving people a nickname that it in some way undermines their position of someone that we can take seriously...reality is it makes me take you less seriously...and also think that you're probably a d:ck...
I'll carry on with my ...'s regardless by the way...and furthermore i'd suggest that anyone that would attempt to use that as a reason to try and ridicule someone else may well be a d:ck...