Whatsapp Hacking

Hacking WhatsApp is near impossible. The only way that you could access someone else's account is being a Middleman in a WiFi network, for example, although there is encryption now (added a few months back).
The only real way to do anything nowadays is to either get access to their phone, or somehow use social engineering to get them to do something, or somehow get control of their mobile number. Spoofing won't work.

Be careful of what you do though, it's definitely being watched very closely and will have severe consequences if you're able to pull something off by some chance.