YAHOO

Somebody that does or thinks about or begins to do something that is seen as too big for them.

Guy one: JJ is such a bozo for thinking that he can take on the entire challenge has he ever even been on the course.
Guy two: That may seem so but he does have the skills he is just trying something that cant be done.
Guy one: Hes always been a yahoo.
JJ: Stfu you guys are lame as fuck