Answer a teenage boy question please?????

So, there is a guy i used to have cles with and we used to say hi to each other all the time, he acted like he liked me. Then he started hanging out with a friend of mine, and they had a fling for awhile(kissed - thats it) then over the summer they stopped talking and now my friend is upset because he wont talk to her anymore. And now, just recently he says hi to me again but says it in a really weird voice, like a cartoon or something. I cant figure it out. Can anyone tell me what this guy is thinking? It bugs me how guys are so unreadable...ugh.