Just wait and see, Just you wait, To do a favor, For you, Definitely, For sure
Structure
Verb[て] + やる
てやる may be used ironically to show anger, or the strong resolve to perform undesirable actions to the listener (threatening), rather than performing favors for others sake. In addition it may also be used to express an intention to show off one’s true ability/power. It’s often used together with expressions like どうせ、絶対、さっさと and the like.