have a memory / mind / head / brain like a sieve

/hav ɐ mˈɛməɹˌi mˈaɪnd hˈɛd bɹˈeɪn lˈaɪk ɐ sˈɪv/

/hæv ɐ mˈɛmɚɹi mˈaɪnd hˈɛd bɹˈeɪn lˈaɪk ɐ sˈɪv/

to have a memory / mind / head / brain like a sieve

to often forget things due to one's exceptionally poor memory

Examples

1. Jannet has a mind like a sieve, so it's impossible for her to forget that.

2. But you have a memory like a sieve I give you that.

3. No, Rob, I meant you have a memory like a sieve.

4. When we say someone has a memory like a sieve, we mean they have a very bad memory and forget things easily!