I'd go out on a limb and say that's probably what sound these beasties (if they were real) would make stampeding through the jungle. I picked up these 4 lovelies at Walmart last summer (less than $5) and finally got around to putzing with them.
Each was given a wash to show off the skin texture of the creature. I highlighted the raised areas and then went in with some details around the face. When I was finished I gave them all a clear coat and then based them.
They turned out decently. Check 'em out.