aha moment 

a moment of sudden insight or discovery.

"A moment of sudden inspiration, insight, recognition or comprehension."

"he had an aha moment when looking at my medications past and present"

aha moment by AnitaRadcliffe May 21, 2023

loof-aha moment 

Having an "aha moment" while in the shower. A common occurrence for many.

You know how I couldn't solve that thing at work? Well, this morning, I got in the shower and had a total loof-aha moment. It just came to me.

loof-aha moment by wordsmitherjim May 2, 2011