While exact origin is unknown, many parallels may be drawn between yingyong and dingdong/ding dong/ding-dong considering their strikingly similar construction, reference to genitalia, and somewhat comparable usage.
May also be shortened to yinger, which has a hard "g" sound.
Sometimes confused with yin yang or possibly even yuanyang.
Sue: "I knowww. I just wanna stick him in my yingyong!"
Sue: "Gawd, Kyle is so hot..."
Mary: "Ew, I can't believe you'd let that man anywhere near your yinger!"
Jaysen: "What on earth are those crazy yingyongs doing over there?"