Be nice to someone. Right now. You don’t even have to spend money or pick up the phone.
Send them an email. Write a note and leave it on their desk.
Message them on Facebook or Twitter or Tumblr with a fond memory and tell them that you’ve been thinking about them.
Text them a picture of something you bought together or a DVD that you watched together.
Make something for someone. Leave a dollar on their keyboard for a snack.
And afterwards, relish in the feeling that you made someone’s day. It’s like magic.