When you're sitting in front of a problem the whole day and cannot put your finger on a solution. Stay 45m longer than necessary, implement and push - yet something tickles your brain - something's just not ... right ... although it works .. but

Get out, walk to the subway, wait for your train - and immediately see the solution as clear as day. Hammer perfect Pseudocode in your phone, get strange looks as you laugh out loud - it was soooo easy and right there in front of you the whole time.You even have already used the exact same function today.
So happy, now you can sleep without a brain-tickle