[bitlevel]

Perhaps Et vous (pluralised you)?

[Centrino]

It's Latin, not French. "Et tu" could be from both languages, but the origin of the saying is what Julius Caesar said to Brutus after being deadly stabbed.

[simias]

The words individually could indeed be French but we'd use the oblique case here, "et toi (aussi), Procter & Gamble?".

Also, I'm not sure what the usage would be in classical Latin, but using the singular to talk about a company in French seems perfectly appropriate. IIRC it's the Brits who like to use the plural for companies and institutions.

[tannhaeuser]

There's also Tu quoque meaning the same thing in Latin.

[CoastalCoder]

Did Caesar actually say that, or was is just a line written into Shakespeare's play?

I've never been clear on that.

[acheron]

Some ancient historians quoted him as saying something similar in Greek, though who knows if it actually happened — ancient historians were often “creative”. I think the source of the Latin phrase is Shakespeare though.

[Xophmeister]

It’s Latin, rather than French.

[cafeoh]

"vous" if pluralized you in French, not in Latin.

[billyjobob]

That’s French, not Latin.