"Go jump in the lake" is specifically referring to the biblical "lake of fire and brimstone" from Revelation 19:20.
It's a polite way of saying Go to Hell, especially in the Bible Belt of the American South.
The most knowledgeable of all beings on earth he would rule the world if only he were able to get out of the lake. he was stuck in WWII when the German tank crew got stuck in a flood and the lake never dried up.
"yo jake, I asked the Panzer of the lake if I would ever get laid"
"Oh cool, what did he say?"
"not in the foreseeable future..."