69 represents a sex position where two persons perform oral sex on each other. This involves each person sucking and licking the sex organ of the other person. Thus, the "6" and the "9" represent human bodies in the opposite position with heads between the thighs of the other.
The goal of 69 is either foreplay or to bring partners to orgasm using the mouth. In male/female 69, the male may ejaculate semen into the mouth of his partner while kissing and licking her vagina. At the same time, the female may experience orgasm while sucking on his penis.
The 69 position can also represent two females mouthing each other's vagina. Two males can have oral sex in the 69 position while playing with each other's genitals. Spectators may watch two persons in the 69 position.