it mostly depends on who the person is and what they like to do, like if they are very social try asking them with a joke like "i will give you a cookie if you dance with me."
or if they are more for mysteries, make a quest of it. write a note that leads them to another note, then to as many as you feel like and at the end have them call you XD
another fun one is the colors
everyone has heard of this? yes?
bassically you can get anything with a variety of colors, balloons or constructon paper would work or even markers/pens. i sugest skittles XD
next place the colors Red,Green,Yellow, and purple
write a note saying, "will you go to the dance with me? return the blue for no, red for yes"
there is no blue XD (not even in skittles)