It is used to describe your very young uncle. He should be in his early twenties. Someone who is popular among girls and strong. Can only be used to describe nice, strong, young uncles (not a child or teen but a young adult). This word is made up of young +uncle. it was made by a Danish girl with a beautiful name that starts with an E.
"Hi how are you?" says Karenwilder
"I am really happy!" says Elva. "My yuncle is coming to visit me really soon and I'm super excited!"