प्रॉप्स are like a way of saying good job या letting them know आप like something या दिखा रहा है appreciation to other fanpoppers. They can be दिया for any reason या even for no reason at all. Sometimes प्रॉप्स are दिया as a reward for participation in certain games या for winning contests, etc. They are kind of like दिखा रहा है "fanpop love" ;)