They should have said "arse".
My patients often get cross as me for saying words like "sacrum" and tell me to stop being posh and just say "arse". Wouldn't go down too well with little old Mavis in her country cottage though ...
"Hiya Mavis, I'm here to check your arse".
And the correct word for "toilet" is bog. Ask anyone.
"Shithouse" is also acceptable depending on who you're talking to (again, probably not little old Mavis)