Je ne vous conseille pas de vous y frotter = I advise you not to meddle with it.
On l’a frotté d’importance (or, comme il faut) = He got a good drubbing.
Fuite
Une bonne fuite vaut mieux qu’une mauvaise attente = Discretion is the better part of valour.
Fumée
Manger son pain à la fumée du rôt = To see others enjoying themselves without joining in.
Il n’y a pas de feu sans fumée = There is no smoke without fire.
[Though the French form is not exact, it is preferred to “il n’y a pas de fumée sans feu” for rhythmical reasons. Compare Plautus, Curculio, i. 1, 53, “Flamma fumo est proxima.”]
Fur