According to Andy Robinson, Garak and Dukat had a one-night fling.
According to canon, Dukat once tried (and failed) to kill Garak.
It is my headcanon that these two events happened on the same night.
Technically, he once tried to execute Garak, which is even funnier.
DUKAT: Damar, arrest this man at once! I want him in front of a firing squad by morning!
DAMAR: Shouldn’t you both get dressed first, sir?
Well, we all know how Garak reacted when Bashir shot him, so…