Vulgar, noisy and excessive, “Do Knot Disturb” is a Bollywood sex farce with almost no sex, and comedy pitched so low you’re more likely to groan than giggle. Don’t say the movie doesn’t warn you: within the first few minutes, you’re treated to a man grunting on a toilet. Like so much in “Do Knot Disturb” — beginning but not ending with that K in “knot” — it has no reason to be.