A noun used to identify a non-related gay male who is regarded as an "honorary uncle" by his friends and their children. Often used as a term of endearment.
"Janie look at this beautiful Tiffany rattle your Guncle Johnny gave you when you were just a baby."
"Janie just got back from a day at the spa with her Guncle Johnny before her senior prom."
"Janie had fantastic centerpieces done by her Guncle Johnny at her wedding reception!"