German: "john", "loo", "bathroom"    {das Klo, pl. die Klos, gen. des Klos, colloq.}

Pronounced: Klo (long O)

Usual Alternatives: die (Frauen/Herren)Toilette, WC, sanitäre Anlagen, Pissoir (men-only)

Colloquial: Scheißhaus, Örtchen, Lokus, Abe, Häuschen, Kloster

Rare Alternatives: Abort, Bedürfnisanstalt, 00 (no clue)

Note: German is highly dialectual especially in vocabulary. What one says in Berlin as colloquial will be different than in München. Stick with Klo or Toilette.