rude slang One will incur severe negative consequences (as a result of something). I'm your boss, so it will be my ass if this report you've prepared for the CEO has any errors. You know it'll be your ass if Mom and Dad catch you sneaking out again.

It will be particularly difficult or require a large amount of effort. Well, it will take some doing, but I think I can get the engine up and running again. I reckon we can get it finished by tomorrow, but it'll take some doing.