deadly dull
very dull. The lecture was deadly dull, and I went to sleep. Her story was really deadly dull. I am sorry I was awake for part of it.
female of the species is more deadly than the male
Prov. In many animal species, the female is poisonous and the male is not, and, by analogy, women are more dangerous than men. Bill: My old girlfriend's been threatening me ever since I broke up with her, but she's too small and weak to do me any harm. Fred: I'd be careful if I were you. The female of the species is more deadly than the male.