He will

feel an uncontrollable urge to ejaculate as his prostate gland and seminal vesicles contract. Once a man has developed an awareness of this sensation, he can then learn to produce a PC contraction before he reaches that point of no return. (Another option is for a man to try practicing this technique on his own while masturbating.)

Most men can do Kegels anywhere, since they're seldom aroused by the exercises; women may want to practice Kegels in private since for them, the increased blood flow to the pelvic region is more likely to spark arousal.