take it to one of those car wash with the super heavy spray hoses and go to town!
I guess you could try and take the back off and pick at it with a tooth pick or something. Don't know how hard it is to get to the speaker/mic openings but that would be your best bet. Oh, and not dropping your phone in ranch would also be helpful! Good luck.
Bring it to Apple.
Most likelly they will replace it for free if you're under warranty.
I had a friend last week that was taking a pic of her birthday cake and dropped her iphone in the cake.
All the frosting didnt clean out so she couldnt hear much from both the bottom and top ear speaker.
They swapped it out for her.
Guys, let's calm down, clearly the OP was on a ranch when this happened. I'm more confused why they were at the bottom of the ranch though, everyone knows that's where the rattlesnakes and the old well are.