Go out on a limb

The limb being talked about here is the branch of a tree and ‘out on a limb’ is an allusion to climbing trees and going just a bit further than is comfortable.

All of us must remember that feeling of not wanting to go further out to reach that apple/ball or whatever for fear that the branch (limb) would break under us.

The first uses of ‘out on a limb’ in a figurative sense, that is, one where there is no reference to actual trees or climbing, come from the USA at the end of the 19th century.

An example of an early use of the phrase is found in the Steubenville Daily Herald, October 1895:

“We can carry the legislature like hanging out a washing. The heft [main part] of the fight will be in Hamilton country. If we get the 14 votes of Hamilton we’ve got ’em out on a limb. All we’ve got to do then is shake it or saw it off.”