A: Do you have Joe’s phone number? I want to ask him something.

B: Sorry I don’t know his number off the bat. I’ll have to look it up in my phone book. I’d better call you back later after I find it.

Note: This informal saying, often used in the United States and Canada, means “immediately, without hesitation.” The origin of this phrase is likely from baseball, where, after a successful hit, the batter will take immediate action and run to first base. The quick response that the batter takes seems to be where the expression gets its figurative meaning of “something being done without delay.” The phrase dates back to the 1880s.