Grave or dangerous (of an accident, illness etc.).
Spiteful, unkind.
Contemptible, unpleasant (of a person).
Awkward, difficult to navigate; dangerous.
Dirty, filthy.
Indecent or offensive; obscene, lewd.
Formidable, terrific; wicked.
Objectionable, unpleasant (of a thing); repellent, offensive.
Sexual intercourse.
Something nasty.
A video nasty.
Pertaining to suicide.
Likely to commit, or to attempt to commit, suicide.
Extremely reckless.
Highly likely to certain to result in the deaths of the participants; dangerous or reckless to such a degree as to be tantamount to suicide for those taking part.
Someone suicidal; someone likely to kill themselves.