Shit-House luck

An unlikely occurrance of good fortune/luck; Very Lucky. Derived from Celtic or Scotish folklore when one is out walking in the wilderness or a remote area and happens to come across an outhouse when in dire neeed of defecating;
Shit-House Luck.

That bastard has Shit-House luck, He's got Shit-House luck, It was Shit-House luck to get out of that one, Shit-House luck prevailed, "Shit-House" luck happened that day