Thingy is an informal noun sometimes used if you can't remember someone's or something's name. For example: “Ask thingy over there, he'll know.”

thingy = thingummy (informal) used to refer to a person or thing whose name you do not know or have forgotten, or which you do not want to mention Examples : It’s one of those thingummies (thingy ) for keeping papers together. Is thingummy (thingy ) going to be there? You know, that woman from the Sales Department? source : Oxford Dictionary

my thingy lol

thingy = sexual organs So now you know what a girl thingy and a boy thingy is.

"thingy"= a word used instead of the correct word which has been momentarily forgotten