I'm going to fake a message saying I have a crush on my friend
Why are you faking the message?
I want to check out his reaction and I want to know how he would react if he found out about my crush on him.
If your feelings for him are real, you shouldn't make light of it and send him fake messages as it may ruin any chance you have of a relationship down the line. Changing from friends to dating can be scary, but being honest is imperative if you want it to work.
I am just in a mood to be playful I might not even go through with it all.
I hope you don't. Being playful is one thing but messing with other's minds is another. I know you can do  better than this.