The can is opened by twisting the plastic seal. While doing this the pressure inside the can is released slowly through the smallest hole on the seal (see picture), thus preventing the soda to spray out if the can has been shaken. When you've had enough for a while you can close the seal with another simple twist, and you're good to go.
Sure, why not? Of course, if you can't finish an energy drink in one sitting, maybe you should, oh I dunno, CONSIDER ASKING YOUR MOMMY FOR A SIPPY-CUP. Me? I'm a grown-ass man -- I could drink three Burns in a row and crush the cans on my face. No -- in my eye. I AIN'T YOUR GRANDMA'S JUICEBOX!
Thanks to Stranger, who has inspired me to sit on my hand.