sick as a dog
- (simile) Very ill.
- I caught that new strain of flu and for three days I was as sick as a dog.
- 1797, John Banks, The Albion Queens, or The Death of Mary, Queen of Scots: A Tragedy, J. Bell, page 32
- Ay, but thou knowest he's as uncertain as the wind; and if, instead of quarrelling with me, he should grow fond, he'd make me as sick as a dog.