What can i do? i only have one friend.

For those of you who aren't aware of it let me first explain why I'm more concerned by this than usual because of the ice bucket challenge I've been nominated to do.
Someone gets nominated to have ice water thrown on them ( usually by the challenger) then they donate money to a charity of their choice then nominate 3 people and tag them on Facebook.
I'm broke, I have no money in my account, I'm living off soup, I have social anxiety, I don't want a video of me up on Facebook and because of my social anxiety I only have one friend I see regularly.
I was saying to my brother how old its getting, he told his friend to nominate me and here I am.
I have no money and one friend, there are people I was briefly friends with on a course but it was a while ago and not their thing, my brother obviously doesn't realise I have social anxiety or friends to challenge and definitely not to throw it on me, but I also can't be the dick who hates charity.

I genuinely don't know what to do

It also doesn't help that my brother was with his friend when he nominated me and when he challenged two others it was silent but when he said my name my brother laughed which made everyone laugh so even without the issue of me having no close friends it looks like a laugh at my expense