A recent letter to Miss Manners (I read this from her syndicated column in The Washington Post) involved an invitation to a BYOB birthday party. Said invite to the party was the followed up by a "suggestion" for a monetary gift, so the birthday boy could travel. Then another such "suggestion" for money was received. After a third "suggestion"--this time accompanied by a "helpful" note that other were giving between $25 and $100, the recipients of such "helpful suggestions" wrote to Miss Manners for advice.
She suggested they quickly turn down the invitation before the host reported them to a collection agency. :D