In the town of Tiring in Cabatuan, Iloilo, planting camote or sweet potato involves three men-- one to plant, the other two to wrestle naked. The wrestling is supposed to bring about plentiful camote vines that are "wrestling with each other". The nakedness is supposed to encourage smooth-skinned tubers. This is done at twilight, for obvious reasons.
This, and other superstitions of the Panay area, are discussed in this 2008 Inquirer article.