as the saying goes: you should learn
german for science
russian for litterature
french for diplomacy
and english for business (it’s so wonderfully ambiguous:p )
now you can add your favorite language to the list …
for instance : Occitan (southern french ) is excellent for braggadoccio and epic sagas …
Another, older and more local saying went: You should speak
French to your equal
German to your servant
Danish to your dog
Pardon, mo pette frere
pepe La peu 
kaice qe Vou dyte ???
qe ya un modos pur vairyfiè si ON éqri pas en SMs issi
et les fotes d’orthopaf on ce fait virer si on en fè ?
Yiargh
D’ailleur pour marc, si on faisait un cumul de tous les forums monocyclists en nombre de posts je pense pouvoir me relever avec acun.fr
Um, No Hablo French?
Moi, je vote pour Laura ! 
Peut-être, mais tu as un avatar sans tour Eiffel 
french is for old people : try Europanto!