Annual event that lasts for two days from the 17th to the 18th of December is made to decrease the most worldsuck. What happens is that people all over youtube make videos supporting their favorite charites and then other people vote for the video. The top five charities that get the most votes will be given 1/5 of the total money donated by everyone. There is a livestream for the P4A that goes on for the whole 48 hours featuring YouTubers from all over. 

You can find more information at the P4A website.