You might simply say the television persoality was comparing the food to having sex (unless your son had been incredibly sheltered, he's probably heard that much at school from older kids or his age peers, or even watching kids cartoons), and go on to say that the chef was very rude about his choice of compliments. It is related to, and offensive for exactly the same reason and to the same degree as using the "F" word.
Ten is usually when parents start having THAT conversation with their kids. I agree that jumping in on that phrase is not a good approach, but if you don't start that conversation soon his friends will. Heck, the schools is going to have that conversation with him in the next 12 months (USA) Some boys are well into puberty by the time they hit eleven, and the girls tend to be a couple of years earlier.
If you don't make a big deal of it, he is more likely to treat it as just another adult description that doesn't make sense on its own, and it provides an opening to start that conversation while you still have a modicum of control.