MATH PUZZLE: Can you replace...

A man was stocking produce at the grocery store when a woman approached, asking, "Excuse me, where's the broccoli? I can't seem to find it."
He replied, "I apologize, ma'am, we're out of broccoli today. We'll have more tomorrow morning."

Resuming his work, he was arranging oranges when the same woman tapped his shoulder and inquired again, "Where's the broccoli? Do you have any?"
He patiently responded, "No, ma'am, we're still out of broccoli. We'll have some tomorrow morning."

Moments later, the woman confronted him once more, demanding, "Why can't I find any broccoli? Where is it?"
The man said, "Please indulge me for a moment. How do you spell 'cat' as in 'catastrophic'?"
She answered, "C-A-T."
He continued, "How do you spell 'dog' as in 'dogmatic'?"
She replied, "D-O-G."
Then he asked, "How do you spell 'fu*k' as in 'broccoli'?"
Puzzled, she said, "There is no 'fu*k' in broccoli."
He exclaimed, "THAT'S WHAT I'VE BEEN TRYING TO TELL YOU, LADY!"