from what kind of dictionary did you chose those nice expressions, nice by their sounds, but what's their meaning?
Qu'est-ce que c'est ce truc ?
Thank you, Gwendy, Gwendo, Gwendissimy. You are full of humour.
Dear Fugendichter, I didn't look up in any dictionary to "choose" (as you said) these expressions. I am used to hearing them or reading them.
Thingy, you should find out in any dictionary to point out something whose name has been forgotten or is unkown. I just looked up in my Oxford dico which says thingy is made of THING + meaningless suffix -y. Other forms would be thingummy, thingamy, thingumabob! Never heard such words.
The whatsit is more a slang word. I suppose it is made of the contraction of what-'s-it. I guess the author of your sentence in bad English would use it. A whatsit often comes to my lips to help me calling something I don't know the name in English.
That's great Sandy! I feel fully satisfied now. Hats off! Turkish people would say sey(the "s" should have a little tail), the Germans would say Dingsbums.
Danke schön, Fugendichter. Would you be Turkish, man? Looking forward to reading you. Sandy
No Sandy, I'm sorry, but I'm not Turkish, I just enjoy to learn the turkish language because of there amazingly agglutinating endings.