phrases that have no eng equivalent:

• pena ajena (sp) - being embarrassed by someone's actions
• l'esprit de l'escalier (fr) - thinking of a comeback too late
• schadenfreude (ger) - taking comfort in someone else's misfortune
• quod erat demonstrandum / QED (la) - "which was to be demonstrated" (way of ending a mathematical, logical or physical proof)
• fremdschämen (ger) - second-hand embarrassment, embarrassment by proxy, vicarious
• baader-meinhof (ger) - where one happens upon an unfamiliar word and afterwards encounters the same subject again, often repeatedly.
• l’appel du vide (fr) - call of the void, the urge to jump from high places when they encounter them

others:

• va fan culo (it) - go fuck yourself
• ipso facto (la) - in and of itself
• le tue l'amour (fr) - a turn-off

TBC