"I don't drink gin in the house" was the first thing that came to mind. Oops.
Why isn't this "Mi ne trinkas ĝin en la domon" ?
Because "domo" isn't the direct object, "ĝi" is. You're not drinking the house, you're drinking "it", so "ĝi" becomes "ĝin".
GG. I did the whole Accusative! =D