YANBU - With some events I've had half a dozen or more people wanting sponsorship and, as soon as one race is out of the way, they want a new challenge to start training for so find another half-marathon/triathalon/bike ride or whatever and the cash requests come again, literally within a couple of weeks. I've started ignoring some of the online requests but the co-workers are the worst as they go round each person in the office and ask them for sponsorship so you are pressurised into not being the mean person who didn't want to help whatever cause it is this time.
Thinking about it, I've realised that I have made fewer donations to my preferred charities over the past year and it is because I've ended up sponsoring people for these charity events. Why don't we all just give money to whatever charity we prefer and cut out all this sponsored running nonsense?
NowThatsWhatICallANickname - While I'm being all 'bah humbug' I hate the charity collections in supermarkets too. In my local supermarket they have bag packers collecting for charity and, if they are only on some tills, you get long queues at the other tills as people try to avoid them.
I especially hate that, because you are put on the spot to give money, you don't really get to find out much about what the charity is and what the money will fund e.g. A lot seem to be local religious groups (Will their special meals for the poor be used to convert people to their religion? Do this church promote anti-gay views? - I don't know because I'm just expected to give there and then to an organisation I've never heard of.)
The most recent occasion was children from a local high school packing bags to raise money for a school trip abroad (not a 'doing voluntary work' style holiday, just a school trip). Personally, I would rather have paid money not to have a teenage boy packing up my sanitary towels but, as usual, the tills with the packers were the ones without the queues. 