It happens in the beginning of Spring and you can see them everywhere you can even use an app for it

Look at this tree behind me

it's just incredible the phase in which they're in right now is full bloom so this happens only for a week and after this they start to actually fall down like snow

So when the petals are falling you eat with your friends or your family underneath the trees and you wait for the petals to rain on you and when the petals fall into your drink it's even better luck