I came to the conclusion that Taemin doesn't give two s about anything anymore.

And this is why:

*smart person voice* 

Throwing the Replay skateboard symbolizes the eradication of his childhood. He is metaphorically saying that his pretty flower boy, crossdressing days are over. He is conveying to his fans that this -Danger- is the real Taemin.

Nethertheless he's still cute as ever!! >.<