When I give my boyfriend head, his leg shakes. Is that normal?
Sexual response is individual to each person, but trembling usually means that a person is getting pretty close to having an orgasm. It happens in women, too, and is sometimes referred to jokingly as the “Shaky Leg Syndrome.”
So don’t worry. The shaking just means that your boyfriend is experiencing an enormous amount of pleasure, which, in turn, means: Good job!