I'll have to go with grapefruit, as I've never actually eaten an orange.
I've had orange juice as a kid, and it gave me such an allergic reaction that I'm not taking the chance. I was at a babysitter's house and had an orange juice popsicle, and then I was picked up to go home. When I got home, I was playing out in the yard and had to lie down because I wasn't feeling well. My mom found me lying in the gutter of our street. So, yeah, no oranges.