Having a larger penis and enjoying a more fulfilling sex life is possible and attainable. Frenulum, Frenum A thin strip of flesh on the underside of the penis that connects the shaft to the head. The time of the first ejaculation of seminal fluid varies but usually occurs about a year after the beginning of accelerated penis growth. An erection of the penis occurs as the spongy tissues of the penis are engorged with blood. These are formed by the fusion of the vas deferens and the seminal vesicles see below.