Justin Timberlake has joined the growing ranks of celebs who've submitted to the Ice Bucket Challenge.

J.T. accepted a Twitter challenge from two Boston fans and gathered more than a dozen folks from his Tennessee Kids fan community for support -- then doused himself with ice water to benefit the ALS Foundation. Justin then passed the challenge on to Jimmy Fallon and The Roots. By the way, Justin's promised donation has earned about 25,000 likes on Facebook so far -- and a couple of hundred promised donations.