Cher is one of many big names who've signed on to a campaign called Sound Off for Autism Speaks, which will raise money to support autism research and advocacy.  For $299, the legendary diva will record the personalized voicemail message of your choice. The only limit: it's got to be either 20 seconds or 250 characters of text.


Other stars participating include Jack Black, Peter Dinklage Mark Hamill, Jim Parsons and Batman himself, Adam West.

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