loo (n.1) Look up loo at Dictionary.com
"lavatory," 1940, but perhaps 1922 (based on a pun of Joyce's); perhaps [Dictionary of American Slang] from French lieux d'aisances "lavatory," literally "place of ease," picked up by British servicemen in France during World War I. Or possibly a pun on Waterloo, based on water closet.
loo (n.2) Look up loo at Dictionary.com
type of betting card game involving a hand of three cards, 1670s, short for lanterloo (1660s), from French lanturelu, originally (1620s) the refrain of a popular comic song; according to French sources the refrain expresses a mocking refusal or an evasive answer and was formed on the older word for a type of song chorus, turelure; apparently a jingling reduplication of loure "bagpipe" (which is perhaps from Latin lura "bag, purse").
From its primary signification -- a kind of bagpipe inflated from the mouth -- the word 'loure' came to mean an old dance, in slower rhythm than the gigue, generally in 6-4 time. As this was danced to the nasal tones of the 'loure,' the term 'loure' was gradually applied to any passage meant to be played in the style of the old bagpipe airs. ["Grove's Dictionary of Music and Musicians," London, 1906]
The refrain sometimes is met in English as turra-lurra. In the game, also the name of the pool or kitty of chips deposited by players before seeing their hands, or of the deposit made in it by a player.