
Have a memory/mind like a sieve
Casual Usage
Used in informal contexts among friends or in relaxed settings, but not in formal situations.

Sorry I missed your party, I have a mind like a sieve and forgot the date!
Self-Deprecating
Often used humorously to admit one's own forgetfulness without being too harsh on oneself.

I'd forget my head if it wasn't attached, I've got a memory like a sieve!
Not Literal
It's an exaggeration and not to be taken literally; it doesn't mean someone forgets everything.

I know I have a mind like a sieve, but I do remember your birthday!
WordUp Chrome Extension
As you browse the web instantly look up words you don’t know.
Get Chrome Extension