You know, the generic “three guys”:
“If I let you have a second helping of tripe, I’ll have every Tom, Dick, and Harry asking for more.”
And their singular friend, So-and-so:
“How come you invited so-and-so to the party but you didn’t invite me?”
So, how do you say these in your language?
I’ll start with Portuguese:
Multiple: fulano, beltrano e sicrano
Singular: “fulano” or “fulano de tal”
In French :
Pierre-Jean-Jacques (Peter, John and Jack)
Madame/Monsieur Untel (Mr./Mrs Onesuch)
Cool 
Im Brazilian, that’s a perfect example.
Do you speak portuguese?
Yes. I have been married to a carioca for many years. I love Brazil and the Portuguese language. As I write this, there lies on my desk a copy of Cidade de Deus by Paulo Lins that I am reading at an agonizingly slow pace.
Welcome to the SDMB!
In Spanish, the singular is “Fulano” as well. If you have more than one, you use, in that order “Fulano, Mengano, Talano, Sultano,…”. That are the only I know, but probably this varies from region to region.
Note that, as in Portuguese, all these made up names rhyme.
Beleza gente !? Nice to see some Brazilians around here !
How about you guys fill out the LOCATION part ?
Fun question.
Multiple: Jan, Piet & Klaas
Singular: Dinges.
:o)
German: Krethi und Plethi (only two, notice? also it´s supposed to have something to do with Cretans and Philistines, though why is beyond my knowledge)
As for the singular: not quite sure, but “Dingsbums” is probably what you´re looking for.
Heh, this is fun.
Australian: “Every man and his dog”
That qualifies as a foreign language, doesn’t it?
Icelandic:
Jón og Gunna (John and … um … his wife.)
This means “the normal people”, “joe six-pack and wife”.
Pétur og Páll (Peter and Paul, of course.)
The meaning of this is more like Tom/Dick/Harry of English.
Dunno about Aussie, but it’s much the same in hebrew - but more like “The whole world and his wife (and the dog)” - the latter if you want to depict a real mob scene, as opposed to the garden variety
Well From what I remember of Colombia we would say “Julano de tal”
And according to my girlfriend (who’s german) you would say: “Hinz und Kunz”.
She does not recognize “Krethi und Plethi” at all though.
UNIX: foo, bar, baz, qux…
Sorry! That was geeky.
Oh yes, Kinthalis, how could I forget Hinz and Kunz… Krethi und Plethi is a bit outdated. “Jeder x-beliebige” also has the meaning of “anyone”.
According to my Danish friend: