My son (4 year old) gets on well with all of the children at his childcare and also has a smaller group of 3 or 4 close friends. However, he is super-sensitive to anything they say: not every day, but often he frets about the clothes he wears, what toys he is going to take for news day, what time he arrives at school etc.
There is one boy who is one of his two best friends who likes to comment on things and ask my son why he is wearing something or why he brought something. It's definitely not teasing, because its his friend, its just part of that boy's personality. This boy gets given lots of toys by his parents and always wears lots of Spiderman etc. clothing so my son thinks he is second best.
My son has never been bullied because he is good at physical activities and is quite likeable, but I am worried that when he goes to school next year worse things are going to be said, which is just life.
How do I harden my son up and teach him to have confidence in himself and appreciate the things he has? Note, I could go out and buy him a bunch of toys or clothes etc. but I don't think that will solve the problem.