Well, I mean, it's not particularly a trick. It's been shown in some cases that the endorphins released durning sex can partially and sometimes completely alleviate the pain caused by a headache or migraine.
What mystical alternate universe is this? Uni actually gathered the courage to give valentines chocolate to Nep Jr.?
Nepgear: "Here is some friendship chocolate for you Uni!"
Uni: "....what?"