to forget something accidentally
etwas versehentlich vergessen (etvas ferzehentlich ferhessen)
"Sorry, it completely slipped my mind to call you."
"Entschuldigung, ich habe völlig vergessen, dich anzurufen." (entshuldigung ish habe fellig ferhessen dish anzurufen)
to eat something quickly
a difficult decision to make
very wise or knowledgeable
to take responsibility for something difficult or unpleasant
to make a serious mistake or spoil something
too difficult to understand