Telethon
A telethon is a fundraising event broadcast on television that lasts many hours or even days, the purpose of which is to raise money for a charitable, political, or other allegedly worthy causes. Most telethons feature heavy solicitations for pledges (promises to donate funds at a later time) combined with variety show style entertainment. The word "telethon" is a portmanteau of "television" and "marathon". The equivalent term for a radio broadcast is a radiothon; most radiothons do not include the entertainment.
Read more about Telethon.