That shit irks me so much! How dare they? By all means put the jar on the checkout counter, but do you really have to try to shame me into giving when I gave 2 days prior? That only makes me NOT want to give as a protest.
I always tell them the truth. I donate online because in Canada, you can write off donations above $20. I send money to Red Cross, and the SPCA mostly. For kids/cancer hospitals I do lotteries. Can't write that off, but I could win big.