Chris Rock Swears for Charity

The Daily Tell reports that Chris Rock, the funny, foul-mouthed comedian, offered at a charity fundraiser to tell off the former lover of the highest bidder.  After a woman pledged $20,000, Rock phoned her ex from the stage and unleashed a stream of profanities at him. 

My question is, how much can she deduct, given that Rock provided a valuable service in exchange for her donation?

TAK