Age-old.

"Hey, do you remember where you placed my book?"

"I forgot."

...

"Well, do you remember it now?"

"I just told you that I don't, right?"

______________________________

It's ironic how we say "I forgot" but still do not remember. Shouldn't we say "I forget" or "I currently don't know"?

It's the why-do-we-call-it-building-when-it's-already-built paradox yet again.