Having a moment that is important to the person but no one else finds it important or relevant to anything going on and they don't care.
Person 1 - EVERYTHING IN MY LIFE SUCKS LOOK AT ME!!
Person 2 - no one cares. Stop having a sakura-moment.
Something that Sakura#0194 would usually do
Sakura: Guys I did it again. I painted my phone case.
Anyone: Sakura Moment