A night on the tiles is a
colloquial Australian term for a hard night's drinking, inevitably resulting in a severe
hangover.
The term is derived from the traditional hard-wearing, easy-to-hose-down floor surface in rough Aussie pubs, and the similar surface of one's toilet at home.
You might overhear in the office on a Friday morning, "fark, mate, you look like you've had a night on the tiles".
NB: this statement, if ever directed at you by an Aussie workmate, should be taken as a compliment (many Aussies admire a piss artist.)