What is the nicest thing you've ever done for someone without their knowledge?

[newsclippings]

Well I haven't done it yet but I was thinking about leaving anonymous notes to my friends and random people in my school that need reassurance of what good people they are or just positivity. For example, "You're beautiful, just believe it." "You think you're alone but someone's always there to listen" "You're perfect just the way you are" I could go on.

Hahah I've done something like this with library books. :]