My father was circumcised in his 60s. My son was circumcised at birth. It can be done at any age.
The answer to "What should I do?" depends on your philosophy on elective surgical procedures, your religious views, your son's medical history/issues, and your ability so far to teach him proper hygiene.
Do kids make fun of other kids for 1000 different reasons? Yes. There's a whole lot you cannot prevent, so you work on raising a resilient child who will not be devastated by some thoughtless or uneducated kid making a remark. Kids are teased for height, weight, skin color and a lot more - none of which you can change.
Do kids make fun of uncircumcised boys? Sometimes. But more and more parents are opting out of circumcision so more boys like your son are in locker rooms and bathrooms. It's like the male equivalent of girls with different sized breasts, right? Bodies are different. Work on teaching acceptance of all body types, not just on conforming to some attitudes you saw on a TV show.
You should have a discussion with your pediatrician and perhaps with a urologist, as well as any pertinent religious leader to sort out your reasons. And after you do all of that, at 8, I think an age-appropriate discussion with your son is in order. The essential thing is that he not feel there is anything wrong with him either way.