Carnival is also transvestitism after all: appearing in different clothes, different personality. No exception in Venice.
Men in women's clothes, usually, the most vulgar as a joke, the better the tease for everybody.
The Gnaga was making its show in the streets - usually a man in disguise - pretending to be a nanny, and sometimes holding a real small baby in her/his arms.
The name Gnaga seems to have originated from "gnao", the meowing of the cat, and the use of an exaggerated falsetto voice made the tease more obvious. And a somewhat similar “catty” appearance on simple peasant clothes was the attire.
The Gnaga would pretend also to be a young woman oppressed by a too rigorous teacher or father and thus could get in contact with young girls looking from the windows.
At times the Gnaga would became too exaggerated in his talking, ending up being beaten up with a heavy club.
It is recorded that, on May 4, 1740 when a Gnaga went a little too extreme in teasing a group of Turks and was almost lapidated (literally!), and the guy had to flee from the city as the Turks were getting ready to shoot him.