Raring to is an American colloquialism meaning extremely eager (to do something). Its exact origins are mysterious, but it seems to have originated in the American South during the early 19th century (though it’s now used throughout the English-speaking world), and raring may come from rearing, where rear means to stand on one’s hind legs. It’s what undisciplined horses sometimes do when anxious to go.
Raring to is generally pronounced rarin’ to, and some writers spell it this way in informal contexts.
Yet over and over in his 15-page opinion, Nixon … insinuates that Stapleton is a scamp rarin’ to ignore the law. [Denver Post]
Dean Howell says he is raring to go after overcoming the first injury setback of his Crawley career. [The Argus]
Summer wound down, but the pop-punk sextet was raring to go, with another catchy single and a new sophomore album last month. [Ottawa Citizen]
Is Jason Statham raring to join the Fast and Furious cast? [Guardian]