The California Raisins were an example of the whimsical, quirky style of the '80s, as well as an example of the nostalgia for '60s music and culture which were so present back then. They were a fictional soul group made up of animated claymation raisins which were featured in commercials for... yep, California Raisins.
Here they are performing "I Heard It Through The Grapevine."
Heres another commercial, this one courtesy of Retro TV. Same song, different commercial.