As an army medic, i take rectal temperatures all the time, the boys call it "the silver bullet" because it looks like a silver bullet at the end. This thing is put up the boys anus when they pass out in the heat because we need an accurate core temperature, 104 its evac to the hospital, under 104, its strip down, cool down and hydrate. We do this in the field, in the middle of a road, or leaning up against a tree, and yes there are a bunch of other guys looking on. Its no big deal, its MEDICINE.
Kids should not be tolerated to refuse or complain about a rectal temperature, it could be the difference between aspirin, or a cold shower and water, or $5000 emergency room visit where they will get their bottoms violated anyway. I had one of my boy scouts drop like a rock after a bike ride. Got overheated, threw up and passed out. I stripped him down naked, and covered him with wet cloths. Took his rectal temp and it was 103. As he came to, started 50/50 gator aid and water, and once he could stand, into a shower with me. I held him up as the cool water ran. Soon his temp was 99 and ok.... After a bit of rest he was fine. BUT, not knowing how to treat him, could have made a huge financial difference to his family.
His doctor said we did exactly right. He asked me why his butt felt wierd, and i told him it was the vaseline i used when i took his temperature. He gasped and said "YOU LOOKED UP MY BUTT" and i said yea buddy, but it was only to make sure you werent seriously sick. He hugged me and said thanks and that it was ok... Get your kids, boys specially used to being examined in their private places because boys play hard, and forget to hydrate all the time. After a hydration crisis, you need to watch him pee and note the color, if strong yellow, he is still dehydrated. Normal boys urine should be almost clear.
Lastly, we are seeing testicular cancer in boys as young as 11. Dad's check the boys bits and make sure there are no hard spots, if so, ER for sure. Do not wait. A few days matter. I teach all the boys how to check themselves and ask them if they check every single morning, in the shower and they all do. One found a lump, fortunately a cyst, but, could have been a tumor as well.