Complimenting complete strangers when walking to class.
When I sent an anonymous letter thanking my teacher for her efforts in hopes that the letter would inspire her to stop being so mean and grouchy all the time.
Many: Giving a rose to a complete stranger who was visibly very unhappy. She asked me angrily what I wanted, my reply was, "Nothing - just thought you could use this". As I continued walking, she softly and very emotionally said, "Thank You"! I now give out roses to strangers almost every month.
Surprising roommates with notes and treats during difficult weeks.
I left my iPhone in the bathroom of the library and didn't realize it was lost. The student who found my phone called all of my friends, until one of them finally picked up and told her where I was working. It was such a nice surprise, especially since she did not have to go through all of that effort to return a phone.
Buying my friends tea and cookies from England because why not??