can't do something for toffee
can't (do something) for toffee
slang Is totally unable to do something. Primarily heard in UK. Oh, you'll definitely beat Sarah for that role in the musical—she's can't sing for toffee.
See also: toffee
can't do something for toffeeBRITISH, INFORMAL
If someone can't do something for toffee, they are very bad at doing that thing. Within a step or two it was clear she couldn't dance for toffee.