By keeping everything cool down there—including your skivvies.
Swindled them all, skivvies and badhachs from the county Meath, ay, and his own kidney too.
"underwear," 1932, nautical slang, of unknown origin. An earlier skivvy/skivey was London slang for "female domestic servant" (1902).
To shirk duty: skive off for a rest
[1919; originally armed forces]