You could always tell him, uh no.
No:
–adverb
1. (a negative used to express dissent, denial, or refusal, as in response to a question or request)
2. (used to emphasize or introduce a negative statement): Not a single person came to the party, no, not a one.
3. not in any degree or manner; not at all (used with a comparative): He is no better.
4. not a (used before an adjective to convey the opposite of the adjective's meaning): His recovery was no small miracle.
–adjective
5. not a (used before a noun to convey the opposite of the noun's meaning): She's no beginner on the ski slopes.
–noun
6. an utterance of the word “no.”
7. a denial or refusal: He responded with a definite no.
8. a negative vote or voter: The noes have it.
–verb (used with object)
9. to reject, refuse approval, or express disapproval of.
–verb (used without object)
10. to express disapproval.
—Idiom
11. no can do, Informal. it can't be done.