off-color

1. Exhibiting bad taste: an off-color joke.
2. Varying from the usual, expected, or required color.
3. Not in good health or spirits.

adjective

1. Bordering on indelicacy or impropriety: blue, earthy, provocative, racy, risqué, salty, scabrous, spicy, suggestive. See decent/indecent.
2. Affected or tending to be affected with minor health problems: ailing, indisposed, low, mean², rocky, sickly. Idioms: under the weather. See health/sickness.

Definition: risque
Antonyms: clean, nice

The adjective has 2 meanings:

Meaning #1: in violation of good taste even verging on the indecent
  Synonyms: indelicate, off-colour

Meaning #2: humorously vulgar
  Synonyms: bawdy, ribald