Such a terrific description of " cheat" 

Torusan

Then

I never be friend with cheating boy;-)

Some examples:

He cheated on an exam. --> He copied answers from a fellow student.

I cheated on my diet. --> I ate more than I should have, or food that I wasn't supposed to (I was supposed to eat an apple for dessert and I had chocolate cake instead).

She cheated death. --> She escaped a dangerous situation that could have killed her.

He cheated on his girlfriend. --> He was dating/having romantic relations/flirting with someone else other than his girlfriend.

To cheat can mean to do something unfair to win at a game or to pass a test.

He always cheats at cards.

She cheated by writing the test answers on her hand.

It can also refer to being unfaithful in a relationship.

She's divorcing her husband because he cheated on her with another woman.