rat and mouse
noun
1
a house. Rhyming slang; first recorded in Songs and Slang of the British Soldier: 1914–1918, John Brophy and Eric Partridge, 3rd edition, 1931. Recorded in the US in 1943 UK, 1931.
2
an informer. Rhyming slang for LOUSE (a despicable person) UK, 1961