Used to negate what was previously said. Commonly used to troll your naïve buddies.
A prominent and best applicable example:
Sure, you can get my ex-gf number... SIKE! That's the wroooong numba!
Sike is when you juke someone. Basically when you promise someone something, then juke them in the last second.
For example:
person 1: hey, can we high-five?
person 2: sure!
person 1-2: *nears their hands*
person 2: sike! *pulls hand away
When you're jokin hahahhaahahaha
Boy: Dad, am I adopted
Dad: Yessir
Boy: Cries, dies, flies, spies, rice.
Dad: SIke, you're just not my son.
Boy: I love you
Girl: I love you too!! <3
Boy: *goes on one knee* "Will you mar-"
Girl: Sike UGLY ASS
*rap battle at a park with many people*
Guy 1" i broke up with my ex girl, here's her number"
Guy 2 *opens paper*
Guy 1 " SIKE thats the wrong number" *jumps into crowd of people*
*gives person a paper of his ex girls number but its fake*
SIKE THATS THE WROWNG NUMBA
OOOOOOOOOOHOHHOOHOOHo