mind like a sieve

Etymology
Since a sieve has many holes, the thoughts in such a mind might be imagined to fall out.

Noun

 * 1)  very poor memory

Translations

 * Finnish: pää vuotaa kuin seula
 * French:
 * German: ein Hirn wie ein Sieb haben,
 * Italian: avere la memoria corta
 * Latvian: caura galva
 * Polish:
 * Russian: па́мять как решето́, голова́ дыря́вая
 * Tagalog: may buslong butas