Why may a guy (18m) be playful and play pranks but then go cold?

[Anonymous]

[Rob1n]

This can have various reasons.

Assuming you are the one he went cold to, you may have done something in his eyes to wrong him. This can be anything: maybe you reacted unintentionally cold to his pranks for an instance.
Or you did not react to his pranks in the way he intended. Maybe he was flirting with you, but you didn't respond flirting back. So he decided to throw in the towel and just go chase someone else.
Lastly, if he is interested in you, he could simply go for the hot and cold dating strategy. Be warm, flirty, and then from one day act cold and distant, so you are wondering what is going on.

Honestly, the best way to know is just ask him.

[Anonymous]

One time fun kinda guy