How would you react if you heard someone call your kid "chunky"??

My 4 year old son is a favorite of his older sisters classmates. They think he is soooo sweet and cute and love giving him hugs and eager hellos every day at pickup. However, lately they have referred to him as being chunky and the moms all give a giggle at this comment.....but I'm realizing that I don't like this term. Am I over-reacting? I know I could very welll be carrying my own personal distaste for comments like chubby, chunky, etc.....but is this considered a no-no for kids??