He sent me clip-on sunglasses for my glasses
Why did he send you clip on sunglasses?
One day, he wearing clip-on sunglasses and I turned to him and said, "Hey man, you have cool sunglasses. Can I try them on?" and I wore them
It's nice of him to get you a gift. Clip on sunglasses are an affordable way to upgrade your standard glasses.
The clip-ons don't fit my new glasses.
Can you return them for another pair? He had no way of knowing you got new glasses that aren't compatible with the clip-ons. You should at least show your appreciation for the gift.