To say something that is often too personal, usually irrelevant, and always unfair. The expression comes from boxing, in which it is illegal to hit an opponent below the belt.
To remind reformed alcoholics of their drinking problem is to hit below the belt.
The most kick-ass character in the film Kick-Ass. Played by the very talented Chloe Grace Moretz, she's a pint-sized, fowl-mouthed 9-year-old superhero who, with the help of her father's training and her advanced experienced with elaborate weaponry, kicks some serious bad guy ass.
Kick-Ass: "How do I get a hold of you?
Hit-Girl: "You just contact the mayor's office. He has a special signal that shines in the sky; it's in the shape of a giant cock."
Hit-Girl (to the drug-dealing villains): "Ok, you cunts. Let's see what you can do now."
To Hit the high "C" is to make the high pitched noise emitted by a man who has just been injured in the genital area. It's a note easily achieved by choir boys and opera singers, but most men will only ever manage to attain such highs when they've sustained a blow to the bollocks.
To induce this noise in a gentleman, use reasonable force when striking the area. Note- REASONABLE force. Excessive force will result in no sound, as the note emitted will be too high for even dogs to hear, or he'll be unconscious, which is no fun for anyone.
"I accidentally elbowed Finn when I went to grab my handbag off the floor. He really hit the high "c", it was hard not to laugh"
"Ferdinand with a very good interception cleanly takes the ball away from Cissé. Now Gerrard comes dancing in like a fairy and oh! It's a kick to the balls from Ferdinand! And there's Gerrard, on his knees, having just hit the high "c""